Alluvium

Loose material deposited by running water, typically streams. Usually a mixture of clay, silt, sand, and gravel.

 

Alluvial Fan

A fan-shaped sloping deposit of alluvium on a flat plain, whose source is usually a narrow canyon located at the head of the fan.

A lowland loose sediment deposited by water run-off -usually forms at the base of mountains in arid and semi-arid environments.

 

Arroyo

A deep dry gully or gulch cut by an intermittent stream.

 

Artesian Spring

A flowing spring, where the water table is higher than the surrounding topography.

 

Badlands

A region of barren land characterized by roughly eroded ridges, peaks, and mesas with sparse vegetation.

 

Bedrock

The solid rock that underlies loose material, such as soil, sand, clay, or gravel. Often exposed in arid climates, due to water and wind erosion.

Box Canyon

A deep canyon, with steep, unclimbable walls, and no exit except the downstream entrance.

 

Braided Stream

A stream that repeatedly divides and recombines, forming many small wandering channels.

 

Butte

A butte is a landform that looks like a tall, skinny hill with steep, almost vertical sides and a flat top. It's usually made of layers of rock, with the top layer being very hard and resistant to erosion (the slow wearing away of rock by wind, rain, and other natural forces). Over a long period of time, the softer rock around the butte gets worn down, but the tougher rock on top helps protect the rest of it, so it stays standing while the land around it disappears.

 

Canyon

A deep gully, caused by extensive persistent erosion relating to that typically of a river, or often in the case of the desert, a wash.

 

Confined Aquifer

A layer of water beneath the surface of the earth that is trapped below an impermeable upper layer. The confining layer is usually composed of clay.

 

Dry Lake

A lake bed, where water accumulates, but later evaporates quickly. Usually a flat, featureless brownish-gray clay, or salt deposits will appear as exposed surface layers after the water has retreated.

 

Dunes

Mounds of unconsolidated sand grains shaped up by the wind. Often temporary and non-stationary.

 

Fault

Cracks in the Earth's crust that are the result of differential motion within the crust. Faults are the source of many earthquakes that are caused by slippage vertically or laterally along the fault. The largest examples occur at tectonic plate boundaries, but many smaller faults are known to exist far from active plate boundaries.

 

Flash Flood

A sudden flood event through a valley, canyon or wash, following a short duration, high intensity rainfall.

 

Flood plain

That portion of a river valley, adjacent to the channel, which is built of recently deposited sediments and is covered with water when the river overflows its banks at flood stages.

 

Hot Spring

A natural spring of water at a temperature of 70 F or above. Heated by thermal activity in a fissure in the earth's crust.

 

Hydrology

The scientific study of water and the way it courses through landscapes, geology, and living things.

 

Intermittent Stream

A stream that runs water in most months, but does not run water during the dry season of most years.

 

Internal Drainage

A drainage system that does not extend to the ocean.

 

Natural Bridge

A naturally-occurring, horizontal undercut remnant in sedimentary rock with the span remaining at the same level or below the supporting end walls.

 

Outcrop

The place where a particular rock unit is exposed at the surface.

 

Quartz

A very hard, glassy-looking mineral; crystallized silicon dioxide; constituent of all acidic igneous rocks and some intermediate and basic rocks; common in metamorphic rocks, as a veinstone, and as a dominant constituent of sandstone (the sand grains are quartz).

 

Quartzite

A granulose metamorphic rock made essentially of quartz.

 

Ravine

A long, deep hollow in the earth eroded by a stream. A ravine is a deep, narrow valley with steep sides, often carved by the flow of water over time. It's typically smaller than a canyon but larger than a gully and is often found in hilly or mountainous regions. Ravines can have streams or rivers running through them, especially after heavy rain or seasonal melting. They're common in areas with soft soil or rock that erodes easily.

 

Salt Lake or Sink

A shallow body of salt water, where, in the cycle of water flowing in and then evaporating, salty minerals are left behind, causing the lake to become increasingly salty.

 

Sand

Loose, granular, gritty particles, resulting from eroded rock. Sand particles are finer than gravel and coarser than dust.

 

Sandstone

A sedimentary rock made of layers of compressed and cemented sand grains.

 

Scarp

An inland cliff or steep slope, formed by the erosion of inclined strata of hard rocks, or possibly as a direct result of a fault. Also called an escarpment.

 

Sedimentary

One of the three main rock types. Formed of mechanical, chemical, or organic sediments transported from their source and deposited as sediment in layers on lake or river bottoms, river sandbars, beaches, and oceans. The sediments can be formed of fragments, formed by precipitation or solution, or formed from inorganic remains (shells or skeletons) of organisms.

 

Seismic

Pertaining to earthquakes or to waves produced by natural or artificial earthquakes.

 

Semiarid

A region receiving an annual precipitation between 10 and 20 inches.

 

Silt

Rock material composed of fine mineral particles intermediate in size between sand and clay.

 

Spring

A natural flow of ground water where the water table is above a sloping land surface.

 

Strata

Layers of material in sedimentary rock. Often one of a number of parallel layers one upon another.

 

Substrate

The base on which a plant or animal grows. Soil is the substrate of most seed plants where rocks, soil, water, or decomposed matter are substrates for other organisms.

 

Terrain

The surface features of an area of land.

 

Uplifting

A geological process in which pressure from within the Earth pushes rock layers (strata) upward. When the pressure becomes too great, the rock breaks and shifts, exposing the once-horizontal layers on their edges. The result is that the rock strata now stand vertically or at steep angles, often visible in exposed cliffs, ridges, or mountain faces. This process plays a major role in shaping landscapes, especially in areas with active faulting or mountain-building forces.

 

Viscous

Describes a substance that is thick and resists flowing. The more viscous a material is, the slower and more sluggish its movement. In geology, viscous lava is lava that is rich in silica (silicon dioxide), which increases its thickness and resistance to flow. These sticky, slow-moving lavas tend to pile up near the volcanic vent, often forming steep-sided volcanic cones or domes.

 

Volcanic

Describes igneous rock that is formed from magma erupted onto the Earth’s surface and then solidified. Volcanic rocks cool quickly, often resulting in fine-grained or glassy textures. These rocks are part of the Earth's dynamic surface processes and are commonly found in regions with past or present volcanic activity.

 

Volcanics

A major group of rocks that form at or near the Earth’s surface through volcanic activity. These rocks originate from molten magma that erupts from a volcano, cools, and solidifies. Volcanic rocks are typically fine-grained due to rapid cooling and include types such as basalt, andesite, rhyolite, and volcanic glass like obsidian. Volcanics play a significant role in shaping landscapes and recording geologic history.

 

Wash

A narrow, dry bed of an intermittent stream, often found at the bottom of a canyon or drainage area. Washes are typically dry for most of the year but can experience sudden, powerful water flow during flash floods. These channels are shaped by erosion and runoff, and they can shift or deepen over time.

 

Watershed

An entire land area that drains or contributes water to a common drainage system, stream, river, or other body of water. Rainfall, snowmelt, and runoff within the watershed flow downhill and collect in channels that lead to a shared outlet point. Watersheds can vary in size from a few acres to vast regions spanning multiple states.