Geology and Waterfall Terminology
Accessibility | A term used to describe how easy or challenging it is to reach a waterfall. |
Angle of repose | The greatest angle of steepness a slope can have while still maintaining its sediment. |
Aquifer | An aquifer is a layer of permeable rock, sand, or gravel that can store and transmit groundwater. Aquifers are crucial for supplying drinking water and irrigation. |
Anorthosite | Anorthosite is a coarse-grained igneous rock composed mainly of plagioclase feldspar. It forms deep in the Earth’s crust and is often associated with ancient tectonic and magmatic activity. In New York, the Adirondack Mountains contain some of the largest exposures of anorthosite in the world. Whiteface Mountain is a prominent example. |
Anoxic | Lacking oxygen. |
Anticline | An anticline is an upward-arching fold in rock layers caused by compressional forces. These structures are common in regions with tectonic activity and can reveal valuable information about Earth’s geological history. In New York, anticlines are visible in the Hudson Valley, particularly in areas like the Catskill Mountains, where folded sedimentary rocks reveal the tectonic forces that shaped the region during the Taconic Orogeny. These formations are also associated with fossil-rich layers and natural resources such as oil and gas. |
Arkose | Arkose is a type of sandstone rich in feldspar, often indicating rapid erosion of granitic rocks. Its pinkish or reddish color comes from the feldspar content and oxidation of iron minerals. In New York, arkosic sandstones are present in the Catskill Mountains, which were part of a vast Devonian delta system. These rocks provide evidence of ancient river systems that transported sediments from eroding highlands into lowland basins. |
B
Basalt | A fine-grained igneous (volcanic) rock primarily composed of dark-colored minerals, including plagioclase feldspar (over 50%) and ferro-magnesian silicates. Basalt, along with andesite, makes up about 98% of all extrusive rocks on Earth. It is commonly found in regions known for volcanic activity, such as Iceland, New Zealand, Northwestern North America, and Japan. New York’s Palisades are a basalt formation formed by the slow cooling of molten material near the end of the Triassic Period (252 to 201 million years ago). |
Base | The bottom of a waterfall or cliff. |
Basin | A basin is a low-lying area of land that collects water, sediments, or both. Basins can form through tectonic subsidence, glacial erosion, or other geological processes. In New York, the Hudson River Basin and the Finger Lakes Basin are notable examples. |
Bed | The bottom of a stream, usually bedrock. |
Bedrock | The solid layers of rock found under sand, dirt or water. |
Block | A type of waterfall characterized by its wide breadth, where the width is greater than the height. While the waterfall spans a wide area, it does not need to form a continuous sheet of water across its entire width. |
Blue Hole | A blue hole is a circular depression or sinkhole filled with water, often forming a pool with strikingly blue coloration due to the reflection of light. These features are typically associated with waterfall geology or karst landscapes in regions with limestone bedrock. In New York, Peekamoose Blue Hole in the Catskill Mountains is a famous example. It is a natural swimming hole formed by water flowing through ancient sedimentary rock layers, and its clear, blue water draws visitors year-round. On private property, Rattlesnake Gulf is also known for having a blue hole. |
Bluff | A bluff is a steep bank or cliff, often formed by erosion along a river, lake, or coastline. Bluffs are typically composed of sedimentary rocks or unconsolidated glacial materials. In New York, Chimney Bluffs State Park along the southern shore of Lake Ontario is a remarkable example. The bluffs are composed of glacial till left behind by the retreating Laurentide Ice Sheet and have been sculpted by wind and wave erosion, creating unique spires and ridges. |
Boulder Cascade | A term used to describe a steep section of a stream where water cascades over, under, and between large boulders piled atop one another. Boulder cascades typically form in constricted areas of a stream, such as canyons or gorges, and are often associated with bedrock breaking off from adjacent cliffs. They also tend to form at the base of waterfalls where rockfalls from the waterfall’s erosion causes boulders to build up at its base. The waterfall at Cayuga Shores WMA has a Boulder Cascade at its base. |
Boulder Garden | Similar to a Boulder Cascade, but across a flat span of a waterway, with water flowing around the boulders. |
Brink | The top of the waterfall. More specifically, the top edge from which water falls. Also referred to as the crest. |
Brook | A stream, smaller than a creek, commonly considered to be fed by a natural spring. |
Buried Valley | A buried valley is an ancient river valley that has been filled with sediment and is no longer visible on the surface. These features often hold aquifers, as the porous sediments within the valley store and transmit groundwater. In New York, buried valleys are found in the Mohawk Valley and along portions of the Susquehanna River Basin. These valleys were filled with glacial outwash and post-glacial sediments, and they serve as vital sources of groundwater for nearby communities. The Niagara Whirlpool’s formation was due to the Niagara River’s eroding away of a buried valley. |
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Cairn | An unnatural pile of rocks, often organized, built as a landmark (for navigation purposes) or as a work of art. |
Calcium Carbonate | Calcium carbonate (CaCO₃) is a chemical compound widely used in various applications. Medically, it serves as a calcium supplement and an antacid. It is also the active ingredient in agricultural lime. Found as a common rock-forming substance worldwide, calcium carbonate is the primary component of seashells and snail shells. Additionally, it is typically the principal cause of hard water. Limestones are an abundant source of Calcium Carbonate in New York State. |
Canadian Shield | A large area of exposed Precambrian rock in North America. The Canadian Shield was the first part of North America to be permanently elevated above sea level and has remained almost wholly untouched by successive encroachments of the sea upon the continent. Diagram. |
Canyon | A narrow, steep valley, ravine or canyon, walled by cliffs, often carved over time by water. A gully, ravine or gorge. We typically do not use the term ‘canyon’ in this region. |
Caprock | A resistant rock layer that lies above less durable formations, providing protection from weathering. Waterfalls flowing over cap rock formations are often classified as Plunge, Block, or Curtain types. The caprock at Carpenter Falls causes a large plunge. |
Cascade | A type of waterfall that flows down a rock face with many jumps. The slope is usually close to 45%. More consistent and defined jumps are commonly referred to as a staircase or tiered falls. Several waterfalls across New York can be considered cascades, the “jumps” can either be large, like with Chittenango Falls, or small, like with Buttermilk Falls. The term Cascade is often used as a general term for a waterfall, regardless if it fits the strict definition of a cascade. |
Cataract | A large waterfall (by volume or height). Also used to describe river rapids with noticeable descent. |
Causeway | A pathway or road, elevated by a bank, usually across water or wetland. Otisco Lake has a causeway on its south end. |
Channel | An eroded portion of the stream bed that directs the stream flow. A channel can be a small groove or a large gorge. |
Chasm | A chasm is a deep, narrow gorge or fissure in bedrock, often created by the erosive action of water over long periods. Chasms can also form along fault lines or where joints in rock have been widened by erosion. A notable example in New York is Ausable Chasm, located near Lake Champlain in the Adirondacks. Chasm is often used interchangeably with Gorge, Glen, and Canyon, but often refers to a more narrow opening. |
Chute | A path of water through a narrow space between rock. Usually turbulent and with high current. |
Cirque | A cirque is a bowl-shaped, amphitheater-like depression carved into a mountain by a glacier. These formations are typically found near the head of a glacial valley and are created by glacial erosion and freeze-thaw processes. Cirques often hold small lakes, known as tarns, after the glacier melts. In New York, examples of cirques can be found in the Adirondack Mountains, where glacial activity during the last Ice Age carved features like the snowbowl cirque on the northeast of Mount Marcy and Lake Tear of the Clouds on the south slope. |
Classical waterfall | A waterfall that is as wide as it is high. |
Clastic rock | A type of rock formed from fragments of pre-existing rock. |
Clay | A hydrous (wet) mix of aluminum and silicate minerals. Usually formed by weathering of silicate rocks (many sedimentary rocks, including shale). Clay retains its water better than mud, as the water is chemically bound to the minerals. This binding, along with the small size, allows for high plasticity. Clay formations will expand and contract depending on water content, yielding unstable geology. |
Concretion | A bulbous mineral concretion usually found within a layer of sedimentary rock. Often called Turtle Stones. They are formed by minerals found within rock layer precipitating towards a nucleus (mineral or bone) and under great pressure, form a rock, harder than the surrounding rock. |
Confluence | A confluence is the point where two or more rivers or streams meet and combine their flow. |
Conglomerate | A type of sedimentary rock comprised of a variety of sand, pebbles, small stones and sometimes shells or fossils. Sometimes called a concretion. |
Contour lines | The lines on a topographic (topo) map that indicate elevation. The closer together the lines are, the steeper the slope. |
Crampons | Crampons are a framework of spikes that are attached to boots to provide traction on snow and ice. (courtesy of wikipedia.org) It is recommended that you use crampons when hiking in gorges and stream beds in the winter. |
Creek | A stream of small size. |
Crest | The top of the waterfall. More specifically, the top edge from which water falls. Also referred to as the brink. |
Current | The flow of water in a stream. |
Curtain waterfall | A type of waterfall that spans a wide section of a stream, characterized by its height being greater than its width. |
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Delta | A delta is a landform created at the mouth of a river where it deposits sediment as it flows into a larger body of water, such as a lake or ocean. Deltas form when the flow of water slows as the gradient reduces and water body widens, causing sediments to accumulate and create flat, fertile land. The prehistoric Glacial Lake Iroquois Delta, located near Rochester, was formed during the retreat of the Laurentide Ice Sheet and is now visible as part of the region’s sedimentary record. |
Discharge | A measurement of the amount of water in a stream that passes a certain point over a period of time. (Usually cubic feet/second). |
Dolostone (Dolomite) | Dolostone, or dolomite rock, is a sedimentary rock primarily composed of the mineral dolomite (calcium magnesium carbonate). It forms from the chemical alteration of limestone by magnesium-rich fluids. Dolostone is typically resistant to erosion and often serves as a caprock for waterfalls and escarpments. A prominent example in New York is the Niagara Escarpment, where dolostone acts as the caprock for Niagara Falls. The dolostone layer resists erosion, while the softer shale beneath erodes more quickly, creating the undercutting that leads to the formation of the falls. Dolostone is also found in the Helderberg Escarpment near Albany and throughout western New York. |
Drainage Basin | See Watershed. |
Drop | Any place along the stream where water falls from one point to another. It could be a free-fall or maintain contact with rock behind. Often used to just describe a waterfall, regardless of its type, or a single distinct part of a waterfall. |
Drumlin | A drumlin is an elongated, teardrop-shaped hill composed of glacial till, formed beneath a glacier as it advances. Drumlins typically have a steep, blunt end facing the direction from which the glacier came and a gently sloping, tapered end pointing in the direction of the glacier’s movement. These landforms are often found in groups called drumlin fields and are composed of a mixture of clay, silt, sand, gravel, and boulders deposited by the glacier. At Chimney Bluffs State Park, located on the southern shore of Lake Ontario, the dramatic clay cliffs and spires are the eroded remnants of a drumlin. Formed during the last Ice Age by the Laurentide Ice Sheet, this drumlin has been significantly shaped by wave action and wind erosion since the glacier’s retreat. The steep cliffs of Chimney Bluffs reveal layers of glacial till, showcasing the composition of the drumlin while offering a striking example of how natural forces continue to modify glacial landforms over time. |
E
Ephemeral | Means changing, not constant. It’s often used in reference to bodies of water that hold water for part of the year and are dry at other times. Ephemeral ponds are often breeding grounds for frogs. Similar to “Vernal.” |
Erosion | The process by which natural forces, such as water, wind, ice, and gravity, remove and transport soil, rock, and sediment, shaping the Earth’s surface over time. It occurs through various mechanisms, including water erosion (rivers and waterfalls cutting channels), wind erosion (abrasion and dune formation), glacial erosion (plucking and abrasion), and gravity-driven processes (landslides and rockfalls). Waterfalls like Niagara Falls and those in Letchworth State Park and Watkins Glen are principal examples of water erosion, where the relentless force of flowing water wears away underlying rock layers, carving dramatic gradients in the rock and causing gradual upstream retreat. While erosion is vital for natural landscape evolution, human activities can accelerate it, leading to environmental challenges such as soil loss and habitat degradation. |
Erratics | Seemingly out-of-place boulders carried to their current location by glacier movement. Identifiable by their roundness and difference in composition from the bedrock. |
Escarpment | An escarpment is a steep slope or long cliff that forms as a result of erosion or faulting, separating two relatively level areas of differing elevations. Escarpments often mark the edge of a plateau or ridge and are commonly associated with geological formations such as fault lines or the retreat of resistant rock layers over time. Specifically in Upstate NY, the Niagara, Onondaga and Portage escarpments contribute to most dramatic gorges and waterfalls. The Niagara Escarpment is responsible for Niagara Falls and the three falls of Rochester, NY. The Onondaga Escarpment contains Akron Falls, Chittenango Falls, Oatka Falls, Serenity Falls and many others. The Portage Escarpment leads to Ithaca falls. |
Esker | An esker is a long, winding ridge of sand, gravel, and other sediments deposited by meltwater streams flowing beneath a glacier or ice sheet. As the glacier melts and retreats, these sediments are left behind, forming a snake-like landform that follows the path of the former subglacial stream. Eskers can often be found in upstate New York, particularly in areas that were heavily influenced by glacial activity, like the Adirondacks, Finger Lakes, and Mohawk Valley regions. |
F
Face | The vertical (or near vertical) surface of a cliff. |
Fan waterfall | A type of horsetail waterfall that spreads horizontally, fanning out, considerably before hitting the base of the falls. |
Fault | A fault is a fracture or zone of fractures in Earth’s crust along which rocks on either side have moved relative to each other. Faults are caused by tectonic forces and can result in the displacement of rock layers, creating landforms such as cliffs, ridges, or valleys. Niagara Falls is partly associated with fault activity. The Niagara Escarpment, over which the falls flow, was shaped by both faulting and erosion. The hard dolomite caprock resists erosion, while the softer shale beneath erodes more quickly, leading to the retreat of the falls and the creation of steep cliffs and plunge pools. Fault-related shifts in the Earth’s crust contributed to the exposure of these rock layers, influencing the location and formation of the falls. |
Finger Lake | The linear, north-to-south glacial lakes of upstate NY are some of the deepest in America. Early map-makers thought they resembled the fingers of a hand, and dubbed them the Finger Lakes. The longest is Cayuga. Seneca is the largest. There are 11 total: Otisco Lake, Skaneateles Lake, Owasco Lake, Cayuga Lake, Seneca Lake, Keuka Lake, Canandaigua Lake, Honeoye Lake, Canadice Lake, Hemlock Lake, and Conesus Lake. Some other adjacent lakes (Cazenovia and Oneida Lakes to the east) are often considered to be part of the Finger Lakes as well. |
Flash Flood | A flash flood is a rapid and intense flooding event that occurs within a short time—typically minutes to a few hours—after heavy rainfall, sudden snowmelt, or dam/levee failure. Flash floods are characterized by their swift onset and strong, fast-moving water, often carrying debris like rocks, trees, and sediment. They are particularly dangerous because of their sudden nature, leaving little time for preparation or evacuation. While not super common in New York, flash flooding does happen. It’s especially risky when hiking in narrow gorges and stream/river beds with impermeable bedrock. |
Floodplain | Flatlands in the watershed of a body of water that have a history of and thus future potential for seasonal flooding. |
Fossil | A fossil is the preserved remains, impression, or trace of a once-living organism from a past geological age, typically found in sedimentary rocks. Fossils can include bones, shells, leaves, tracks, or other evidence of ancient life. New York has a rich fossil record, particularly from the Devonian Period (approximately 419 to 359 million years ago) when the region was covered by a shallow inland sea. This environment preserved many marine organisms, and New York’s fossils are often found in shale, limestone, and sandstone formations.
Cairo, New York is home to possibly the oldest discovered forest, with fossil trees dating back 387 million years ago. |
Friable | Easily broken apart or burrowed through. |
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Genesee Valley | The Genesee Valley is a prominent region in western New York State, centered around the Genesee River, which flows northward from the Allegheny Plateau to Lake Ontario. Shaped by the retreat of the Laurentide Ice Sheet during the last Ice Age, the valley features a mix of glacial deposits, fertile soils, and dramatic landscapes. The river carved deep gorges, including the iconic Letchworth State Park, often called the “Grand Canyon of the East,” where waterfalls cascade over layers of shale, sandstone, and limestone. The glacial activity left behind drumlins, moraines, and other features that define the valley’s topography. Historically, the Genesee Valley has been a hub for agriculture due to its rich alluvial soils, making it a key part of New York’s “Breadbasket” during the 19th century. Indigenous peoples, including the Seneca Nation of the Haudenosaunee Confederacy, thrived in the region, using the river and fertile lands for farming and trade. European settlers later established towns and mills along the river, leveraging its flow for transportation and industry. The Genesee Valley Canal, constructed in the 19th century, further connected the region to larger trade networks, though it was later replaced by railroads. Today, the Genesee Valley remains vital for agriculture, particularly dairy and crop farming, while also offering significant recreational and ecological value. Parks like Letchworth and Genesee Valley Greenway preserve its natural beauty and history, attracting visitors for hiking, kayaking, and wildlife observation. Urban centers like Rochester, situated at the river’s mouth, contribute to the valley’s cultural and economic importance. |
GIS | Geographic Information Systems. A database format that links data tables to maps with the capacity to easily manipulate data geographically. Many governments use GIS systems to track data, such as watersheds and property ownership, of their municipalities. |
Glacier | A glacier is a large, slow-moving mass of ice formed from accumulated snow that compresses into ice over time. Glaciers flow under their own weight and shape the landscape through processes of erosion, transport, and deposition, carving valleys, depositing sediments, and creating landforms such as moraines, eskers, and drumlins. The most recent glacier to cover New York State was part of the Laurentide Ice Sheet during the last Ice Age, also known as the Wisconsin Glaciation. This glacier reached its maximum extent about 20,000 years ago and began retreating roughly 17,000 years ago as the climate warmed. The glacier completely melted from the region by approximately 11,000 years ago. The retreat of the Laurentide Ice Sheet profoundly shaped New York’s landscape. It carved the Finger Lakes, formed the Hudson Valley, left behind features like drumlins, moraines, and eskers, and deposited glacial erratics (large boulders transported by the glacier). It also influenced soil composition and drainage patterns, shaping ecosystems and human settlement. |
Glen | A glen is a small, secluded valley, often long and narrow, and usually found in hilly or mountainous areas. While the term is commonly associated with Scotland, it is also used in other parts of the world. The terms Gorge and Glen are often used interchangeably in New York. |
Gorge | A gorge is a deep, narrow valley with steep, rocky walls, often carved by a river or stream over thousands or millions of years through erosion. Gorges are typically associated with areas of resistant rock that have been gradually worn away by flowing water, creating dramatic and rugged landscapes. Example: The Watkins Glen Gorge in New York, formed by Glen Creek cutting through layers of shale and sandstone. |
GPS | Global Positioning System. A technology that uses US military satellites to triangulate the position of a GPS receiver. Can also provide elevation data. Software, in conjunction with a GPS receiver can provide direction, speed and provide navigational data. GPS receivers can be accurate within 2 meters (6′). |
Gradient | In geology and geography, gradient refers to the slope or steepness of a land surface, river, or stream. It is typically expressed as the vertical drop (elevation change) over a horizontal distance. Gradients influence many natural processes, such as the speed of water flow in rivers, erosion rates, and the formation of landforms. |
Granite | Granite is a coarse-grained, intrusive igneous rock composed mainly of quartz, feldspar, and mica. Known for its durability and resistance to weathering, granite forms from the slow cooling of magma deep within the Earth’s crust. It is commonly used in construction and monuments due to its strength and aesthetic appeal. Granite can be found in a few regions of New York:
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Grist Mill | A mill where grain is ground into flour. |
Gulf | In the context of waterfalls in the Northeast, a gulf is another term for a gorge or canyon. |
H
Hanging Valley | A hanging valley is a smaller, elevated valley that ends abruptly at a steep cliff, high above the floor of a larger main valley. Hanging valleys form when a tributary glacier joins a larger glacier but does not erode as deeply as the main glacier. When the glaciers retreat, the tributary valley remains “hanging” above the main valley. These features often have waterfalls where the stream from the hanging valley drops into the main valley below. Kaaterskill Falls in the Catskill Mountains is an example of a waterfall associated with a hanging valley. The upper valley, formed during the last glacial period, lies above the main valley and is drained by Kaaterskill Creek, which plunges dramatically over the cliff into the lower valley. This drop is a characteristic feature of a hanging valley. |
Horsetail waterfall | A type of waterfall that maintains partial or constant contact with the rock behind it. Usually thin. Warsaw Falls is a good example of a Horsetail waterfall. |
Hudson Valley | The Hudson Valley is a prominent region in New York State, stretching along the Hudson River from the Adirondacks and Lake Champlain in the north to the New York City metropolitan area in the south. Geologically, the valley was shaped by the retreat of the Laurentide Ice Sheet during the last Ice Age, with meltwater carving the river’s path and creating proglacial lakes like Lake Albany, which deposited fertile sediments. The valley’s underlying geology consists of ancient metamorphic rocks like schist and marble, as well as sedimentary rocks such as shale and sandstone. The Hudson Valley has long been a vital corridor for human settlement. Indigenous peoples, including the Lenape, lived in the region for thousands of years, utilizing its abundant resources and waterways. During European colonization, the Hudson River became a key route for trade and transportation, connecting New York City to the interior. The valley’s agricultural richness supported early settlements, and its strategic location played a pivotal role during the Revolutionary War. The region remains important today, with the Hudson River acting as a major economic and ecological resource. Modern Hudson Valley landscapes include rolling hills, riverfront towns, and fertile floodplains that sustain farming and winemaking. Urban centers like Albany, Poughkeepsie, and Yonkers are balanced by protected natural areas, including the Catskill Mountains and Hudson Highlands. The region is celebrated for its scenic beauty, cultural and art heritage, and environmental diversity, making it a cornerstone of New York State’s identity. |
I
Ice Bridge | An ice bridge is a natural formation of solid ice that connects two land masses or spans a body of water, typically forming during extremely cold weather when rivers, lakes, or portions of the sea freeze completely. Ice bridges are often temporary and depend on consistent freezing temperatures to maintain their structure. Before the construction of permanent bridges, ice bridges frequently formed across the Niagara River below Niagara Falls during winter. These natural crossings were used by pedestrians in the 19th and early 20th centuries. One famous incident occurred in 1912 when part of the ice bridge broke, resulting in a tragic accident. Ice bridges in the Niagara Gorge are rare today due to changes in water flow regulation and the installation of an ice boom on Lake Erie, which prevents the flow of ice into the Niagara River. |
Ice Contact Deposits | Ice contact deposits are sediments deposited by meltwater streams in direct contact with glacial ice. These deposits often form unique landforms such as kames, eskers, and outwash plains. The kames and eskers in Mendon Ponds Park near Rochester were formed as meltwater streams deposited sand and gravel in glacial cavities during the Laurentide Ice Sheet’s retreat. |
Ice Dam | An ice dam forms when an ice build-up or a glacier blocks a river or stream, causing water to back up and form a lake. When the dam melts or breaks, it can result in catastrophic flooding. Lake Iroquois, a precursor to modern Lake Ontario, was formed by an ice dam that blocked meltwater from flowing northward. When the dam melted, the water drained into lower elevations, reshaping the surrounding landscape. Prior to to an artificial Lake Erie-Niagara River Ice Boom being installed at the Niagara River inlet in Buffalo, ice from Lake Erie would flow down the Niagara River and build up above and below Niagara Falls, causing ice dams and ice bridges. One event caused Niagara Falls to stop flowing. Other events caused damage to infrastructure. |
Ice Scour | Ice scour refers to the erosion and smoothing of bedrock caused by the movement of glaciers, which carry debris like rocks and sediment that scrape the underlying surface. Glacial striations in the Adirondack Mountains and Finger Lakes region are evidence of ice scour, where grooves in the bedrock show the direction of glacial movement. Seneca Lake, the deepest of the Finger Lakes, was overdeepened by this process. |
Igneous Rock | Igneous rocks form through the cooling and solidification of molten rock, either as intrusive rocks (formed below the Earth’s surface) or extrusive rocks (formed at the surface). Intrusive rocks cool slowly, forming large crystals, while extrusive rocks cool quickly, resulting in fine-grained textures. The Adirondack Mountains are primarily composed of ancient intrusive igneous rocks, such as granite and anorthosite, formed over a billion years ago during the Precambrian era. These rocks are exposed due to tectonic uplift and erosion, making the Adirondacks a unique geological region. |
Isostatic Rebound | Isostatic rebound occurs when the Earth’s crust, compressed under the immense weight of glaciers, slowly rises after the ice melts and the weight lifted. This process can alter landscapes and water flow patterns over time, including reversing rivers and draining ancient lakes. The Hudson River and Finger Lakes regions experienced isostatic rebound after the Laurentide Ice Sheet’s retreat. The subtle rise of the land has influenced drainage patterns, including the flow direction of rivers like the Genesee River, which used to flow in two branches and through Irondequoit, NY. |
J
Jasper | Jasper is an opaque, fine-grained variety of quartz that is often red, yellow, or brown due to iron impurities. Jasper forms as silica-rich fluids permeate rock, creating colorful bands or nodules. It is commonly found in association with sedimentary rocks and ancient volcanic activity. In New York, jasper can be found in the Adirondack Mountains and in riverbeds such as those in the Hudson Valley. Jasper is sometimes collected for its ornamental value and use in jewelry. |
Jet | A jet describes the forceful, narrow flow of water as it exits a constrained space. This can occur in waterfalls with high velocity due to pressure buildup, such as Bridal Veil Falls of Niagara Falls, where water shoots through a tight space in the riverbed before cascading down. |
Joint | A joint is a natural fracture or crack in a rock where there has been no significant movement parallel to the surfaces of the fracture (unlike faults). Joints form as a result of stress in the Earth’s crust, caused by processes such as cooling, unloading, tectonic forces, or shrinkage of rocks. Joints often occur in sets or systems with a regular pattern and can vary in size, from microscopic to several meters long. They serve as pathways for water, which can enhance weathering and erosion. Joints play a critical role in shaping landscapes by providing points of weakness where rocks can break, erode, or weather. They also influence the formation of features such as caves, cliffs, and canyons. In New York State, joint systems are visible in the rock formations of the Finger Lakes gorges (such as Watkins Glen), where water exploits these fractures to carve deep, narrow valleys. |
Jump waterfall | A type of waterfall that freefalls from the caprock to the base. Also known as a ledge or plunge, the bedrock behind the falls is eroded further than the stronger more resistant caprock, sometimes leading to a shallow cavern behind the falls. Carpenter Falls is a jump waterfall. |
K
Kame | A mound or hill of sand and gravel deposited by melting glaciers. Kames are found in regions shaped by glacial activity. Kames can be found all over Central and Western NY. Mendon Ponds Park and Black Creek Park in the Rochester region are particularly good examples. |
Karst | A geological landscape formed by the dissolution of soluble rocks, such as limestone or dolomite. Karst features include caves, sinkholes, and underground streams. Akron Falls is a good example of a waterfall in a region filled with Karst topology. |
Kettle (lake) | Are created when large blocks of ice break off from a retreating glacier and become buried in glacial sediments. Over time, the ice blocks melt, causing the overlying sediment to collapse and form a depression. If the depression fills with water, it becomes a kettle lake. Devil’s Bathtub of Mendon Ponds Park in Monroe County, is a notable glacial kettle. Many of the Lakes in the Adirondacks are also Kettle Lakes. |
Knickpoint | A point of abrupt change in the gradient of a river, often marking the location of a waterfall or rapid. This term isn’t often used in the New York region. |
L
Lacustrine | Pertaining to lakes or lake environments. This term often describes sediments deposited in ancient or existing lakes. Lacustrine deposits are abundant in the Finger Lakes region, where glacial lakes left behind fine-grained sediments, particularly in valleys and basins. |
Landslide | The sudden movement of rock, soil, or debris down a slope, often triggered by heavy rain, erosion, or seismic activity. Landslides are relatively common in New York State due to its varied terrain, geological conditions, and environmental factors. The state’s steep slopes, found in regions like the Catskills, Adirondacks, Hudson Highlands, and Finger Lakes, are particularly prone to instability. Much of the landscape was shaped by the retreat of the Laurentide Ice Sheet, which left behind glacial till, clay-rich sediments, and over-steepened valleys, all of which are susceptible to failure when saturated. Sedimentary rocks like shale and clay layers, common in the Hudson Valley and Finger Lakes, become slippery when wet, while layered bedrock with softer materials underneath can erode and destabilize slopes. Intense rainfall, rapid snowmelt, and human activities such as construction and deforestation further increase landslide risks by saturating soils and weakening slope stability. Minor seismic activity, though rare, can also trigger landslides in already unstable areas. These factors make landslides a recurring hazard, particularly in glacially influenced regions like the Hudson Valley, Catskills, and Finger Lakes, where heavy rainfall and human development contribute to slope failures. |
Laurentide Ice Sheet | The Laurentide Ice Sheet was a massive glacier that covered much of North America during the last Ice Age, peaking around 20,000 years ago during the Wisconsin Glaciation. Spanning millions of square miles, it extended from the Arctic to as far south as present-day New York, Ohio, and Illinois, and from the Rocky Mountains in the west to the Atlantic Ocean in the east. This ice sheet, up to 2 miles thick in some areas, profoundly reshaped the landscape through processes of erosion, deposition, and glacial scouring. In New York State, the retreat of the Laurentide Ice Sheet, which began about 17,000 years ago, created numerous glacial landforms, including the Finger Lakes, kettle lakes, drumlins, eskers, and moraines. Its meltwaters also formed proglacial lakes like Lake Iroquois (a precursor to Lake Ontario) and influenced modern river systems such as the Hudson. The legacy of the Laurentide Ice Sheet is evident in New York’s rugged terrain, fertile soils, and glacially carved valleys. |
Ledge | A flat or gently sloping rock surface, often forming the edge of a cliff or steep slope. In the context of a waterfall, a ledge can be considered a type of waterfall that has a single distinct step. Or it can refer to a particular step in a multistep waterfall. Wiscoy Falls is an example of a waterfall with several steps. |
Limestone | A sedimentary rock, consisting mostly of calcite, found in locations where prehistoric marine environments once existed. Limestone colors vary depending on composition. Pure limestone is white. Grey indicates clay impurities. While red is usually colored by iron oxide. Limestone layers are generally thicker than shale layers. The limestone in New York State formed millions of years ago during the Paleozoic Era, particularly in the Ordovician, Silurian, and Devonian periods, when the region was covered by warm, shallow seas. Limestone is abundant in many parts of New York State, particularly in areas shaped by ancient marine environments. Key regions include:
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Lithification | The process in which sediments compact under pressure and start to form rock. Fluids are lost from the sediments as pressure tightens the space in between grains. Heat generated from the pressure contributes to the bonding of sediment. This process can take thousands of years. |
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Marble | Marble is a metamorphic rock formed when limestone undergoes heat and pressure, causing its calcite grains to recrystallize. This process creates a denser rock with a distinctive crystalline texture. Marble formations are not common in New York, but several deposits exist. They are found in the Taconic Mountains and Hudson Highlands regions, where ancient limestone deposits were subjected to metamorphism during tectonic events. New York’s marble has historically been used for building materials and monuments. Tuckahoe Marble is one of the more historically significant marbles to come out of New York. Quarried in Westchester County, was used from the late 1800s into the 1930s to construct America’s early public buildings in the neoclassical style. |
Meander | A meander is a winding curve or bend in a river, formed as water erodes the outer banks and deposits sediment on the inner banks of its channel. Meanders are common in mature rivers and streams with gentle gradients. The Genesee River, south of Rochester, exhibits meanders as it flows through the relatively flat landscape before entering the steep gorge at Letchworth State Park. Fall Creek flows relatively straight through Ithaca as it descend into the Cayuga Lake Valley, but upstream from the gorge, where the land is relatively flat, it meanders back and forth for miles. |
Meltwater | Meltwater refers to water released from melting snow or ice, including glaciers. Meltwater from winter snow build-up provides an excellent window for viewing waterfalls with impressive flow. The waterfalls in Cayuga Shores Wildlife Management Area usually dry to a trickle by spring, but are fully flowing and highly impressive in late winter due to meltwater. |
Meromictic Lake | A lake in which the layers of water do not mix. Lakes and ponds usually turn over their waters as a result of seasonal temperature change. Meromictic lakes are either very deep and have steep sides or are highly saline at the bottom, preventing turn-over. These lakes generally have massive collections of undisturbed sediments at the bottom with very slow rates of decay. |
Metamorphic rock | Metamorphic rocks are formed when pre-existing rocks—igneous, sedimentary, or other metamorphic rocks—are transformed by heat, pressure, and chemically active fluids within the Earth’s crust. This process, called metamorphism, changes the mineral composition, texture, and structure of the rock without melting it. In New York State, metamorphic rocks are predominantly found in the Adirondack Mountains, Hudson Highlands, and parts of the Taconic Mountains. The Adirondacks, one of the oldest mountain ranges in North America, feature extensive exposures of Precambrian metamorphic rocks like gneiss, formed over a billion years ago during ancient tectonic and mountain-building events. The Hudson Highlands contain metamorphic rocks such as schist and quartzite, which were formed during the Taconic Orogeny, a mountain-building event that occurred around 440 million years ago. Additionally, marble is found in areas like the Taconic and Hudson Valley regions, where ancient limestone deposits were subjected to high heat and pressure. |
Mineral Vein | A mineral vein is a sheet-like deposit of minerals formed when mineral-rich fluids fill cracks in rock and crystallize. These are often associated with ore deposits. The Adirondacks are known for their mineral veins, including deposits of iron, garnet, and quartz. The region was historically mined for iron and garnet, with the latter still being extracted today for industrial use. |
Moraine | A moraine is a ridge or accumulation of debris (glacial till) deposited by a glacier. Moraines form at the edges of a glacier, including its terminus (end) or along its sides. They are composed of unsorted materials ranging from clay to large boulders. The Valley Heads Moraine spans the south ends of the Finger Lakes, which had southern-flowing rivers prior to the last ice age. The moraine blocked the southern flow of water, causing the lakes to form and the flow to head northward. |
Mohawk Valley | The Mohawk Valley is a significant geological and geographic region in New York State, stretching along the Mohawk River as a natural corridor between the Atlantic Coastal Plain and the Great Lakes region. Shaped by the retreat of the Laurentide Ice Sheet during the last Ice Age, the valley was carved by glacial meltwater and filled with sediment from proglacial lakes like Glacial Lake Albany. Its geology features layers of sedimentary rocks such as limestone, shale, and sandstone, along with glacial landforms like eskers, kames, and drumlins. These formations, combined with fertile soils deposited by glacial and fluvial processes, define the valley’s modern landscape. The valley’s strategic location made it a vital route for Indigenous peoples, including the Mohawk Nation of the Haudenosaunee Confederacy, who utilized its resources for agriculture, trade, and travel. During European colonization, the Mohawk Valley became an essential link between eastern and western New York. The construction of the Erie Canal in the 19th century further enhanced its importance as a trade corridor, a role continued today by the New York State Thruway and major railroads that follow its path. Ecologically, the Mohawk Valley supports diverse habitats, including wetlands, riparian zones, and surrounding forests near the Adirondack Mountains and Catskills. Its fertile floodplains sustain agriculture, while urban centers like Schenectady, Utica, and Rome contribute to its economic and cultural significance. The valley’s rich geological history and continued role as a transportation and agricultural hub highlight its enduring importance in New York State. |
Mouth | The outlet where a stream or river empties into a pond, lake, or ocean. |
Mudstone | Mudstone is a fine-grained sedimentary rock composed mainly of clay and silt-sized particles, typically less than 0.0625 millimeters in diameter. It forms in low-energy environments such as lake beds, river floodplains, and deep marine basins, where fine sediments settle and are compacted over time. Mudstone has a smooth texture and appears in a range of colors, including gray, brown, black, red, and green, depending on its mineral content. Unlike shale, mudstone does not break into thin layers but instead fractures irregularly. Its formation in calm environments often results in excellent fossil preservation. In New York State, mudstone is abundant in regions like the Catskills, Finger Lakes, and Hudson Valley, where it dates back to the Devonian Period, around 419 to 359 million years ago. In the Catskill region, mudstone was deposited in ancient floodplains and deltas and often contains fossils of early land plants and freshwater fish. In the Finger Lakes, mudstones interbedded with shales and sandstones are exposed in gorges, revealing evidence of ancient marine environments. These rocks also contribute to the state’s landscapes, forming softer slopes and valleys as they erode more easily than harder rocks. Economically, mudstone is used for bricks, cement, and as a natural barrier in landfills and reservoirs. |
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Niagara Escarpment | The Niagara Escarpment is a prominent geological feature stretching from western New York into Canada and beyond. It is a steep, long cliff formed by the differential erosion of bedrock layers, with hard dolostone capping softer shale and sandstone beneath. This escarpment is most famously associated with Niagara Falls, where the Niagara River plunges over the resistant dolostone caprock, creating one of the most iconic waterfalls in the world. The escarpment was shaped by glacial and fluvial processes during the retreat of the Laurentide Ice Sheet about 12,000 years ago. |
Natural Bridge | A natural bridge is a rock formation where erosion has carved an arch or bridge-like structure in solid bedrock. These features are often formed by water flowing through joints or cracks in the rock, gradually enlarging them until a bridge remains. While natural bridges are less common in New York compared to regions like the American Southwest, small examples exist in upstate New York. One notable example is the Natural Stone Bridge and Caves in the Adirondacks, near Pottersville. This site features a massive stone arch carved by flowing water through ancient marble bedrock. The bridge spans Trout Brook and is surrounded by caves and other karst features, showcasing the effects of erosion on soluble rock. It is one of the largest natural marble bridges in the eastern United States. |
Newborn falls | A relatively new falls, usually not well defined and always close to the main body of water they empty into. Because they have not been around for long, they have not eroded away the rock enough to recede further away from the gully they empty into. They are often seasonal and sometimes man-made by construction or terraforming. |
Nunatak | A nunatak is a peak of rock that protrudes above an ice sheet or glacier, remaining uncovered by ice during glaciation. Nunataks serve as isolated refuges for plants and animals during glacial periods and are significant for studying ancient ecosystems. While nunataks are more common in areas like Greenland or Antarctica, features resembling them exist in the Adirondack High Peaks region. Whiteface Mountain and other Adirondack summits likely protruded above the Laurentide Ice Sheet during parts of the last Ice Age. |
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Oligotrophic | An environment that offers little to sustain life. Skaneateles Lake is an oligotrophic Finger Lake. |
Oncolite | A rare, spherical lime rock formed by blue-green algae growth on a pebble or shell core. Hard when wet, brittle when dry. |
Outcrop | An outcrop is a visible exposure of bedrock or ancient geological formations at the surface of the Earth. In New York, notable outcrops are found throughout the Adirondack Mountains, where ancient Precambrian rocks like gneiss and anorthosite are exposed. In the Catskills, sedimentary rock outcrops such as shale and sandstone reveal the Devonian-age history of the region, including fossilized remains of marine life. Additionally, the Niagara Gorge showcases outcrops of dolostone and shale, which illustrate the layering of rock that contributes to the formation of Niagara Falls. New York’s highway system’s construction led to hundreds of artificial outcrops as roads were cut through rock layers, exposing otherwise hidden bedrock. |
Overdeepening | Overdeepening refers to the process by which glaciers carve valleys deeper than their surrounding terrain, often creating steep-walled basins or troughs. This occurs as a glacier erodes soft bedrock more rapidly than harder rock, forming U-shaped valleys or basins. A prime example of overdeepening in New York is the formation of the Finger Lakes, such as Seneca Lake and Cayuga Lake. These lakes were carved by glaciers that eroded the valleys deeply, leaving basins that were filled with meltwater as the glaciers retreated. |
Oxbow Lake | An oxbow lake is a crescent-shaped body of water formed when a meandering river cuts off one of its loops, leaving a standalone water feature. These lakes are common in floodplain areas where rivers have low gradients and frequently change course. In New York, oxbow lakes are found along the Mohawk River, where the river’s meandering path has created several abandoned channels. Oxbow Lakes can also be found along the Genesee River, near Belfast, NY. |
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Pegmatite | Pegmatite is an igneous rock with exceptionally large crystals, often forming from the final stages of magma cooling. Pegmatites are valued for their mineral diversity, including quartz, feldspar, mica, and sometimes rare gemstones. In New York, pegmatites are found in the Adirondack Mountains, where they often contain feldspar and mica used in industrial applications. The Barton Garnet Mine in the Adirondacks also has pegmatitic textures associated with its rich mineral deposits. Smooth and round pegmatite stones can also be easily spotted along Lake Ontario‘s various beaches. |
Plateau | A plateau is an elevated flat or gently sloping area, often formed by uplift or volcanic activity. Plateaus are often eroded into dramatic cliffs, gorges, and valleys over time. In New York, the Catskill Plateau is a prominent feature, formed from Devonian sedimentary rocks uplifted during the Alleghanian Orogeny. The plateau is dissected by streams and rivers, creating waterfalls like Kaaterskill Falls and gorges that expose its layered rock structure. |
Plunge (waterfall) | A type of waterfall that freefalls from the caprock to the base. Also known as a ledge or jump, the bedrock behind the falls is eroded further than the stronger more resistant caprock, sometimes leading to a shallow cavern behind the falls. Carpenter Falls and Tinker Falls are good examples of plunges. Niagara Falls can also be considered a plunge. |
Plunge Pool | A plunge pool is a deep, bowl-shaped depression found at the base of a waterfall, formed by the erosive force of falling water and sediment. These pools are often carved into bedrock and can vary in size depending on the waterfall’s volume and height. Taughannock Falls in the Finger Lakes region has a prominent plunge pool at its base. |
Pool | A section of a stream where the water is deep and slow moving. |
Pothole | A pothole is a circular or cylindrical hole drilled into bedrock by swirling water and sediment. These features are often found in riverbeds or at the bases of waterfalls, where turbulent water spins debris that erodes the rock. In New York, potholes are visible at Ausable Chasm in the Adirondacks, where the Ausable River has carved deep, circular depressions into the Cambrian sandstone. Small, but numerous potholes can be found throughout Watkins Glen as its many waterfalls eroded the rock bed and receded over thousands of years. |
Precambrian rock | Rock formed during the Proterozoic and the Archaean eras that formed the first continents. The oldest rock on Earth. |
Punchbowl | A type of waterfall that descends in constricted form, into a pool at the base, rather than cascading over rocks at the base. |
Pyrite | Pyrite, often called “fool’s gold,” is an iron sulfide mineral with a metallic luster and brassy-yellow color. It forms in a variety of geological environments, including sedimentary and metamorphic rocks. In New York, pyrite is found in the Hudson Valley and Catskills, often in association with Devonian shales. Small nodules of pyrite can also be seen in the Marcellus Shale, a formation rich in organic material and associated with fossil fuels. |
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Rapids | Rapids are sections of a river where the water flows quickly and turbulently due to a steep gradient, rocky riverbeds, or sudden drops in elevation. Rapids often occur in areas where rivers flow over resistant bedrock. Synonymous with “whitewater.” In New York, several waterways have notable rapids that adventurers seek out for whitewater rafting. Here are some examples:
The most notorious rapids in New York are the Niagara Rapids and Whirlpool, which are downstream from Niagara Falls. These class VI rapids have standing waves that reach 10 ft tall. Traversing them is highly dangerous and strictly prohibited. |
Ribbon waterfall | A waterfall much taller than it is wide. Taughannock Falls, Carpenter Falls, and Eagle Cliff Falls are good examples of Ribbon Waterfalls. |
Riffle | A section of a stream where the water is more turbulent, shallow and the flow is reduced. Identifiable by aerated water flow. |
Rill | A rill is a small, narrow channel formed by flowing water on the surface of soil or sediment. Rills are often precursors to larger gullies and can be formed during heavy rainfall or runoff. In New York, rills are commonly seen in areas with loose, erodible soils, such as agricultural fields in the Genesee Valley and along streambanks in the Finger Lakes region. Over time, rills can deepen and expand into larger erosional features. |
Riparian Zone | The zone between land and a river or stream. These zones are critical ecosystems that stabilize stream banks, reduce erosion, and support diverse plant and animal life. In New York, riparian zones are vital to areas like the Hudson River Estuary and along the Genesee River, where they help maintain water quality, provide wildlife habitats, and mitigate flood impacts. Restoring and enhancing riparian zones is a massive and important conservation strategy in the last few decades, leading to the creation of several preserves and greenspaces on land containing waterfalls. Restoration projects in urban riparian areas like Rochester’s High Falls aim to restore and preserve these important ecosystems and buffer zones. |
River | A large stream, usually used as a waterway. The major Rivers in New York are:
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River Terrace | A river terrace is a flat, step-like surface along a river valley, representing the former level of a riverbed. Terraces form when a river erodes downward, leaving remnants of its older floodplain at higher elevations. In New York, river terraces can be observed along the Hudson River and Mohawk River. These terraces were shaped by glacial meltwater during the retreat of the Laurentide Ice Sheet and indicate previous stages of river flow and sediment deposition. |
Rock Striation | Rock striations are linear grooves or scratches on bedrock surfaces, caused by the movement of glaciers that drag rocks and sediment across the ground. These features indicate the direction of glacial movement. In New York, rock striations are visible throughout the Adirondacks and the Finger Lakes regions. For example, at Blue Mountain and in the gorges of Watkins Glen State Park, glacial striations provide evidence of the Laurentide Ice Sheet’s movement across the landscape. |
Rockfall | A rockfall occurs when rocks detach from a cliff or steep slope and fall due to gravity. Rockfalls are common in regions with fractured bedrock, where freeze-thaw weathering and erosion weaken the rock over time. In New York, rockfalls are frequent pretty much everywhere there are cliffs. Watkins Glen State Park, Taughannock Falls State Park, and other Finger Lakes region gorges have rockfalls that require significant downtime in early spring as park crews clean up trails, repair damage, and remove unstable rocks from cliffs. |
Run | A section of a stream where the flow is smooth and uninterrupted. |
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Sandstone | Sandstone is a sedimentary rock composed primarily of sand-sized mineral grains, typically quartz and feldspar, bound together by natural cementing materials like silica, calcite, or iron oxide. It forms from the compression and lithification of sand deposited in environments such as rivers, beaches, deserts, and shallow marine settings. Sandstone often displays visible layers, or bedding, and its durability makes it a significant geological and architectural resource. In New York, Potsdam Sandstone is a notable example found in the Adirondack region. This Cambrian-age sandstone, formed over 500 million years ago in a shallow marine environment, is renowned for its durability and uniform composition. It is widely exposed in Ausable Chasm, where the Ausable River has carved through layers of Potsdam Sandstone, creating dramatic cliffs and waterfalls. Additionally, Potsdam Sandstone has been used historically as a building material throughout New York State, including for foundations and structures in cities like Albany and Syracuse. Medina Sandstone is a type of fine to medium-grained, reddish-brown to gray siliceous sandstone that formed during the Silurian Period, approximately 425 to 420 million years ago. Its rich iron oxide content gives it a distinctive reddish color, though other shades like gray and buff are also common. This reddish color made it a highly prized building material in the 1800s and it can be found in several upstate public buildings and landmarks. |
Schist | Schist is a metamorphic rock with a foliated, flaky texture caused by the alignment of minerals like mica. It forms under high heat and pressure and often sparkles due to its mineral content. It’s also one of the funnier rock names. In New York, schist is prominent in the Manhattan Schist, a metamorphic formation that underlies parts of New York City and extends northward into the Hudson Highlands. The schist was formed during the Taconic Orogeny and is critical in supporting the city’s skyscrapers due to its strength. |
Scree | Scree consists of loose, broken rock fragments that accumulate at the base of cliffs, steep slopes, or mountain faces due to mechanical weathering, such as freeze-thaw cycles. Scree can be found along most cliffs and gorges in the Finger Lakes region. |
Sediment | Sand, pebbles or any particulate matter carried and deposited by water flow. |
Sedimentary rock | Sedimentary rocks are formed by the accumulation and compaction of sediment, such as sand, silt, clay, and organic materials, over millions of years. These rocks often preserve fossils and display layers called bedding planes. In New York, sedimentary rocks dominate much of the Finger Lakes region, Hudson Valley, and the Catskills. For example, the Devonian-age shale, sandstone, and limestone of the Finger Lakes gorges, such as Watkins Glen State Park, highlight how water erosion cuts through layers of sedimentary rock, creating stunning waterfalls and cliffs. |
Segmented (waterfall) | Used to describe a waterfall that splits into 2 or more distinct drops. Kaaterskill Falls is one of the most notably segmented waterfalls. |
Series (waterfall) | A group of waterfalls, usually separated by pools or sections of the stream. Sometimes one is not visible from another. Sometimes considered part of the same falls. Watkins Glen‘s “Glen of Pools” section, which is just before Rainbow Falls is a series of small waterfalls and plunge pools. |
Shale | A type of sedimentary rock, usually grey, formed from mud or fined grain silt, deposited in thin, easily fractured and porous layers. Because of its ease of erosion and common presence, shale contributes greatly to the characteristic NY State waterfall look. |
Sinkhole | A sinkhole is a depression or cavity in the ground caused by the collapse of underlying bedrock, often in areas with soluble rock like limestone. Sinkholes are associated with karst landscapes, where water dissolves the rock over time. In New York, sinkholes are less common but can be found in areas with limestone, such as the Helderberg Escarpment near Albany. The region’s karst features, including caves and sinkholes, formed in ancient Devonian limestone, showcasing the effects of water erosion over millions of years. Small sinkholes can be found in Western New York near Akron Falls and Indian Falls, another region with karst features. |
Slump | A slump is a type of mass wasting where a portion of land moves downslope along a curved surface, creating a rotational movement. This is often caused by water saturation, erosion, or unstable soil conditions. Slumping contributes to erosion. Slumping can be seen along the steep riverbanks of the Hudson River and in the gorges of the Finger Lakes, where soft shale and sandstone layers can become unstable after heavy rainfall. Slumping can also be seen along the Genesee River Gorge at Letchworth State Park, near middle falls. In New York, sinkholes are less common but can be found in areas with limestone, such as the Helderberg Escarpment near Albany. The region’s karst features, including caves and sinkholes, formed in ancient Devonian limestone, showcasing the effects of water erosion over millions of years. Small sinkholes can be found in Western New York near Akron Falls and Indian Falls, another region with karst features. |
Solution Cave | A solution cave forms when acidic water dissolves soluble rock, such as limestone or dolostone, creating underground voids, passages, and chambers. Howe Caverns and Secret Caverns in Schoharie County are the most famous solution caves in New York. They formed in Devonian limestone and feature underground rivers, stalactites, stalagmites, and an underground waterfall, showcasing the effects of water erosion on soluble bedrock. |
Spur | A spur is a ridge or projection of land that extends into a valley, often formed by river erosion or glacial activity. Spurs are commonly seen as interlocking ridges in V-shaped river valleys. In New York, spurs are visible along the Hudson River Valley and in the gorges of the Genesee River at Letchworth State Park, where river erosion has carved into the plateau, leaving ridges and steep cliffs. |
Staircase waterfall | A type of waterfall that flows in a series of consistent steps, resembling a staircase. Triple Cascade in Watkins Glen, and Wiscoy Falls are good examples of staircase waterfalls. |
Stratigraphy | A branch of geology, studying rock and sediment layers. |
Stratum | A layer of rock or soil, of the same composition, distinguishable (but not necessarily of different composition) from surrounding layers. Lower stratum are geologically older than those above (except in rare cases). This is referred to as the Law of Superposition. |
Stream | A body of water with a detectable current and confined within a bed. Smaller than a river and not necessarily navigable. (Also referred to as a brook or creek). |
Striation | See Rock Striation |
Superfund | A federal law that budgets for the clean-up of highly contaminated areas. Prioritizing residential areas and sites where contamination can spread. |
Superposition (Law of) | A principle of geology that states that rock and sediment layers are arranged in time sequence, with older layers on the bottom and more recent layers on the top. Geological activity can disrupt this order. |
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Talus | Talus refers to a general accumulation of large, angular rock fragments at the base of a cliff, steep slope, or mountain face. The pieces of rock are typically coarse, ranging from large boulders to smaller chunks. Talus forms through gravity-driven processes like rockfalls and landslides. Similar to Scree in definition but there are some differences: Talus is made up of larger fragments of rock and forms slopes that can be quite steep, often 30–45 degrees. A large Scree slope of small limestone and shale stones can be found just left of Taughannock Falls. While talus fields comprised of massive boulders can be found in several spots in the Adirondacks: around Chapel Pond, throughout the Wilmington Notch, Bald Mountain near Old Forge, and along the shores of Lake Champlain. |
Talus Cave | A talus cave is a cave-like opening formed by the accumulation of large boulders and rock debris in talus slopes. Unlike solution caves formed in limestone, talus caves are created by the spaces between fallen rocks. The Talus Caves below Wallface Cliff in the Adirondack Mountains is a talus cave network formed in a boulder field. These caves provide habitats for bats and other wildlife and are often explored by hikers and spelunkers. |
Tiered waterfall | A type of waterfall that flows in a series of distinct steps or drops. Also referred to as a staircase if the steps are uniform in size and distance, resembling stairs. |
Topographic map | A geographic map indicating elevation using contour lines. Commonly referred to as Topo maps. An excellent tool for locating waterfalls. There are several rules to note when viewing topographic maps: The rule of Vs: sharp-pointed vees usually are in stream valleys, with the drainage channel passing through the point of the vee, with the vee pointing upstream. This is a consequence of erosion.The rule of Os: closed loops are normally uphill on the inside and downhill on the outside, and the innermost loop is the highest area. If a loop instead represents a depression, some maps note this by short lines radiating from the inside of the loop, called “hachures”. Spacing of contours: close contours indicate a steep slope; distant contours, a shallow slope. Two or more contour lines merging indicate a cliff. See our Topographic Maps section for more information. |
Tributary | A tributary is a smaller stream or river that flows into a larger river, contributing to its flow. Tributaries play a key role in shaping river systems, transporting water, sediment, and nutrients. In New York, the Genesee River has numerous tributaries, such as Canaseraga Creek and Oatka Creek, which contribute to its flow as it carves the Genesee Valley. Similarly, the Mohawk River serves as a major tributary to the Hudson River, significantly increasing its volume as it flows toward the Atlantic Ocean. |
Travertine | Travertine is a dense, crystalline form of calcium carbonate deposited by mineral-rich waters from hot springs, rivers, or caves. It forms terraces, pools, or crusts where water evaporates and leaves behind dissolved minerals. Although more common in geothermal areas like Yellowstone, travertine can be found in New York where spring water flows over limestone. For instance, small travertine deposits occur in areas of the Helderberg Escarpment and limestone-rich regions of Central New York, such as near natural springs. |
Tufa | Tufa is a type of porous limestone formed through the precipitation of calcium carbonate from freshwater sources, such as springs, rivers, or lakes. It often forms around waterfalls or areas with slow-moving, calcium-rich water. In New York, Minnewaska State Park Preserve (home to Awosting Falls) in the Shawangunk Ridge is known for its tufa deposits, where calcium carbonate precipitates from groundwater and coats rocks along streambeds and waterfalls. Tufa formations are also found in smaller spring-fed areas throughout the Hudson Valley. |
Turbidity | Turbidity is a measure of the cloudiness or haziness of a liquid, caused by the presence of suspended particles that scatter and absorb light. It is often used to assess the clarity of water in streams, rivers, lakes, and reservoirs. High turbidity indicates that a water body contains a large number of particles, which can include sediment, silt, algae, organic matter, and pollutants. High turbidity doesn’t necessarily indicate polluted waters. For instance, Esopus Creek in the Catskill Mountains is prone to high turbidity during heavy rainfall when sediments from surrounding areas are washed into the water. High turbidity in the Hudson River estuary also occurs naturally due to tidal action stirring up sediments from the riverbed. |
Turtle Stone | See concretion. |
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U-Shaped Valley | A U-shaped valley is a steep-sided, flat-bottomed valley carved by the erosive action of a glacier. Unlike V-shaped valleys, which are formed by rivers, U-shaped valleys are broader and deeper, with smooth walls that reflect the glacier’s movement. The Genesee River Valley at Letchworth State Park exhibits characteristics of a U-shaped valley in some areas, where glacial activity deepened and widened the valley. In the Adirondack Mountains, glacially carved valleys like those near Avalanche Pass showcase the classic U-shaped profile formed during the last Ice Age. |
Ultramafic Rock | Ultramafic rocks are igneous or metamorphic rocks with very low silica content and high levels of magnesium and iron. These rocks originate from the Earth’s mantle and are rare on the surface. Also known as ultrabasic rocks. Ultramafic rocks can be found in the Adirondack Mountains, particularly in areas where ancient tectonic activity exposed deep crustal and mantle rocks, such as gabbro and peridotite formations. If you hold one of these you are holding a piece of the Earth’s mantle. |
Unconformity | An unconformity is a gap in the geological record caused by erosion or non-deposition of sediment over a significant period. It represents a boundary between older and younger rock layers, often marked by differences in rock types or angles. In the Helderberg Escarpment near Albany (and passing through Thatcher State Park), an unconformity separates Devonian sedimentary rocks from older Ordovician rocks, showcasing millions of years of missing geological history. |
Undercut | An undercut is an erosion feature formed when water removes material from the base of a cliff or bank, creating an overhanging ledge. This process often occurs at waterfalls or riverbanks. Although difficult to see because of its high flow, Niagara Falls features a prominent undercut at the base of the dolostone caprock, where the softer shale beneath erodes faster, causing the falls to recede over time. A great example of a waterfall with a massive undercut is Ludlowville Falls in Lansing, NY. |
Underfit Stream | An underfit stream is a small stream or river that flows in a valley much larger than it appears to have the capacity to form. These streams often occupy glacial valleys and are remnants of larger rivers or meltwater channels. Many streams in the Finger Lakes, such as those feeding into Seneca Lake, are underfit streams occupying valleys originally carved by massive glacial meltwater flows. The Cohocton River and Canaseraga Creek flow through a valley 20x wider than their annual peak. The Hudson River below the Catskills is considered underfit in parts of its valley, which was significantly deepened and widened by glacial action. |
Upstream Migration (Waterfall) | Upstream migration refers to the process by which a waterfall gradually moves upstream over time due to erosion at its base. This occurs as the force of falling water undercuts the rock, causing collapse and retreat. Over thousands of years a waterfall can migrate upstream for miles due to this erosive process. Examples in New York: Niagara Falls is a textbook case of upstream migration. Since the end of the Ice Age, the falls have retreated approximately 7 miles from their original position near the Niagara Escarpment. |
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V-shaped Valley | A V-shaped valley is a steep-sided valley formed by the erosive action of a river cutting into the landscape. These valleys are typically found in regions with active stream erosion and minimal glacial influence (or soft rock that eroded quickly after the last ice age), giving them their characteristic narrow and pointed shape. The Esopus Creek Valley in the Catskills is an example of a V-shaped valley, shaped by the creek’s powerful erosion through softer sedimentary rocks. |
Vertical Jointing | Vertical jointing refers to fractures or cracks in rock that are oriented vertically, often formed by tectonic stress, cooling of igneous rock, or unloading of overlying material. These joints play a key role in shaping landscapes by allowing water to infiltrate and erode rock along the fractures. Vertical jointing is prominent in the gorges of the Finger Lakes, such as Watkins Glen State Park, where water exploits these joints to carve narrow, steep-sided canyons through the Devonian shale and sandstone. |
Volcanic Rock | Volcanic rock refers to igneous rock that forms from the rapid cooling of lava or magma at or near the Earth’s surface. This type of rock is often fine-grained and includes basalt, rhyolite, and andesite. While we have no volcanoes in New York State, we do have volcanic rock. In the Adirondack Mountains, ancient volcanic rocks are exposed in certain areas, such as Whiteface Mountain, where Precambrian basaltic and rhyolitic rocks reveal the region’s deep tectonic history. |
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Waterfall | A waterfall is a feature where water flows over a vertical drop or series of steep drops in a river or stream. Waterfalls form due to variations in rock resistance, tectonic activity, or glacial erosion, which create steep gradients in the riverbed. Waterfalls can also be man-made, either unintentionally (See Holley Canal Falls), from the construction of a dam (such as Burt Dam), or as a work of art (such as the NYC Waterfall Project). Various sources have definitions as to what really is a waterfall versus something else, such as height, volume of water, or other factors. On this site, the definition is pretty loose. If it has water, and that water is falling, and it’s something to be enjoyed, we’ll add it to the list. |
Watershed | An area of land where all the water drains into a common water body, such as a river, lake, or ocean. Watersheds are defined by topographical divides and are essential for understanding hydrology and water management. The Hudson River Watershed spans much of eastern New York, covering over 13,4000 square miles, draining into the Atlantic Ocean. |
Weathering | The process of breaking down rocks and minerals at the Earth’s surface through physical, chemical, or biological means. Weathering does not involve movement of material (unlike erosion).
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Wetland | A wetland is an area where water covers the soil or is present near the surface for at least part of the year, creating unique ecosystems. Wetlands play crucial roles in water filtration, flood control, and biodiversity support. The Montezuema Wetlands Complex, located at the north end of Cayuga Lake, is a significant wetland area that supports diverse plant and animal life, particularly migratory birds. |
Wind Gap | A wind gap is a valley, notch, or pass in a mountain ridge that was once occupied by a river but no longer contains flowing water. It forms when the river is diverted or captured by another stream. The Hudson Highlands feature wind gaps created by ancient rivers that were redirected during glacial periods. |
Whirlpool | A whirlpool is a rotating body of water that forms when currents meet or water flows unevenly around obstacles, creating a vortex. Whirlpools can range from small eddies to large, powerful maelstroms capable of pulling objects underwater. They occur in rivers, oceans, or any water body where water flows converge or accelerate. Whirlpools form when converging water currents meet, creating turbulence and rotational motion, or when water flows around obstructions such as rocks or underwater features, forcing it to spiral. Rapidly changing water levels, such as during tidal shifts, can accelerate flow and contribute to vortex formation, as can the turbulence generated by water plunging over falls or rapids and hitting still water below. These dynamic interactions create the circular motion characteristic of a whirlpool. One of the most famous whirlpools in the world is the Niagara Whirlpool located in the Niagara River Gorge, downstream from Niagara Falls. This whirlpool was created by the intense water flow as the river makes a sharp 90-degree turn through the gorge. The high velocity of water from the upstream rapids, combined with the river’s constriction and sharp turn, generates a powerful vortex. |
