Geomorphology Flashcards
Define Karst
A term that is applied to the topography of a region which is underlain by limestone, dolomite, gypsum, or other rocks which can be affected by dissolution.
What are 4 conditions necessary for the development of karst terrain?
- a soluble rock (limesstone) at or near the surface
- A dense rock, highly jointed and thin-bedded.
- Entrenched valleys below uplands underlain by soluble rock and well-jointed rocks
- A region of moderate to abundant rainfall
Sinkholes: What? Environment?
Circular depressions that are commonly funnel-shaped and can be a few feet to a hundred feet in diameter. They are the most commonly observed karst feature.
Solution sinkholes
Occur when rainwater comes into contact with carbonate bedrock either directly or though a thin covering of soil.
Cover-subsidence sinkholes
Form where sand overlies the carbonate bedrock.
Cover-collapse sinkholes
Develop where there is a thick layer of clay above the soluble bedrock.
Dripstone
A depositional karst feature of travertine deposits that result from the CaCO3-rich water dripping from the ceiling of a cave or cavern.
Helictite
A depositional karst feature of an irregular twig like deposit that forms in a cavern where there is not enough water to form drips, but where the surface remains damp allowing the CaCO3 to grow in any direction
Travertine
A depositional karst feature of a deposit of CaCO3 precipitate that can be found in limestone caverns coating the cavern walls, floors, and ceilings.
Blind Valley
An erosional karst feature. It is a valley that ends at a swallow hole due to a prolonged period of upstream erosion above the sinkhole.
Cavern
Large caves that may extend in any direction, have one or several levels, and are created by the solution of limestone along joints and bedding planes.
Hum
Isolated hill remnants due to erosion by solution in karst terrain.
Karst Window
A hole in the ground in which one can observe an underground stream flowing from one cavern to another. A hole in a cavern which breaks the surface.
Lapies
Grooved or fluted surface resulting from the solution of limestone at or near the surface in an area of high relief. Grooves commonly result in knifelike ridges.
Natural tunnels & bridges
Features produced by the underground flow of water in karst terrain. Bridges are formed when the tunnel sections collapse.
Polje
An elongated basin with a flat floor and steep walls formed by solution of a previously faulted or folded structure.
Sink
The point at which a sinking creek ends, often in an observable swallow hole.
Sinkhole or Karst plain
A limestone plain exhibiting sieve-like characteristics resulting from numerous sinkholes intercepting any surface waters and diverting them to subsurface channels.
Sinkhole ponds or karst lakes
A pond or lake resulting from the clogging of a (doline) sinkhole by clay that perches water above the water table.
Sinking creeks
Any surface creek or stream which disappears underground in karst terrain. Many disappear in a swallow hole.
Solution valley or karst valley
A transitional feature between surface and subsurface drainage in an area of clastic rocks. It is a special type of a blind valley.
Solution-subsidence trough
A non-tectonic feature, up to 10 miles long, resulting from concurrent subsidence and solution along joints or faults.
Swallow Hole
A hole in the bottom of a sinkhole which allows surface water runoff or streams to flow into the subsurface cavities.
Terra rossa
A red clayey (CL-CH) soil found mantling the ground surface and extending into joints or fractures resulting from surface or near surface solution. It is usually found on moderate to gentle slopes.
Uvala
An elongated karst window that has occurred by the collapse of an extensive portion of a subsurface waterway. These features can extend from 1000 ft to a mile or more.
What did continental glaciation cover during the last Ice Age?
Central and northern U.S.
Where is Alpine glaciation found?
Mountainous areas of Alaska, in the higher elevation of the Rockies, the Sierras, and the Cascades.
Drift
It is all rock and associated material that has been carried by and deposited by a glacier, glacial ice, or water running from a glacier.
Drumlin
An elongated ellipsoidal feature which can be composed of a wide variety of material ranging from till to relatively large rock fragments. The streamlined hills are usually clustered and found near the terminal or recessional moraines.
Esker
Serpentine shaped stratified deposits that develop as the load carried by the stream flowing beneath, within, and above the glacier, once the glacier becomes stained and is dropped.
Kame & Kame terrace
A small hummock or terrace of ice-contact drift that has resulted from the deposition of sediment either in crevasses at the surface of the glacier, or on the irregular surface of stagnant glaciers, or from streams flowing at the edge of the glacier along the contact of the ice with the valley wall. Sediments are usually stratified and contain poorly sorted sands (SW) and gravels (GW).
Kettle
A depression in the postglacial terrain formed by the melting of a large stagnant ice bock which allows for the settlement of the overlying glacial drift.
Arcuate terminal moraine
An arcuate moraine that has been deposited at the terminus of the glacier. marking the furthest progression of the glaciation.
Ground moraine
Can be composed of both the material contained within the glacier and the material being moved at the base of the glacier.
End moraine or Terminal moraine
Found at the maximum extent of a continental glaciation.
Recessional moraine
Moraines that have formed during a temporary hiatus in the retreat of the ice sheet.
Outwash plain
A broad plain composed of outwash: stratified depbirs that is carried by meltwater streams both in front of and beyond the terminal or end moraine.
The outwash plain is typically comprised of coarser grained materials (SW, GW) closer to teh terminus of the glacier grading to finer materials with increased distance.
Swell & Swale topography
Till deposits rich in clay that may result in a gently undulating surface whihc often is also found in areas that have had multiple glaciations
Till
An unsorted, unstratified glacial deposit composed of a herterogenous mixture of clay (CL), silt (ML), sand (SW), gravel (GW), and boulders.
It is usually unconsolidated and deposited directly by a glacier
Lacustrine Plains
A plain that has formed by the filling of a lake with lake sediments and alluvium which has been deposited along the margin of the glacier.
Characterized by very flat alley bottoms in hilly terrains.
Moraines
A mound or ridge composed of accumulated of accumulated glacial drift or till deposited directly by the glacier.
Composed of a heterogenous collection of unsorted and unstratified clay (CL), silt (ML), sand (SW), gravel (GW), and boulder.
Many large clasts are faceted and have striations or polish due to abrasion while the glacier moved.
Arête
Cirque
Col
Fjords and Fiards
A submerged glacial trough or valley at its seaward end resulting from the raising of sea levels as the glacier melts.
Fiards
Glacial polish
Glacial steps or stairway
Glacial Trough
A steep-sided valley that extends down from the cirque in which glacial action has widened and deepened an existing valey.
Hanging Valley
Horn
Monuements (tinds)
Paternoster lakes
Tarn
A small deep lake formed in a cirque basin
Trough Lakes
Truncated or faceted spur
A ridge in a pre-glacial valley that has been truncated by the abrasion of glacial action as it straightened the valley.
Alluvial Fans: How do they develop? Grain sizes and sorting?
Base Level
Bed Load
Runoff
Sheet Flow
Sheetwash
Deltas
- Occur when streams enter lakes or seas and the flow branches out. Sedimentation occurs because of the change in gradient.
- Topset and bottomset beds consist of deposiuts of finer grained silts (ML) and clays (CL)
Gravel Bars
(Sand Bars)
GP and SP can develop midstream when the flow velocity of the water declines where it borders with a higher velocity in the stream.
Bars are usually linear in the flow direction.
Often relatively well sorted or poorly graded deposits.
Natural Levees
Braided Stream
Stream Terraces
Ripple Marks (2 types)
Asymmetrical ripple marks indicate directional current.
Symmetrical ripple marks indicate oscillating water.
Peneplains
Pediments
Inselbergs
What are 3 proceeses that need to occur to develop a stream channel?
Where do meander streams occur
How do Parallel Streams develop?
Dendritic Streams
Radial Pattern Streams
Deranged Stream Pattern
Braided Stream Pattern
What 3 Stream patterns occur with lithologic or structural control?
Wave Cut Beach or Wave Cut Platform
Marine Terrace
A wave-cut platform that has been exposed onto and by uplift or a lowered sea level.
Headlands
Sea Cliif
Scarp-like features found at the seaward side of marine terraces and are caused by erosion from wave action
Sea Arches and Caves
Stacks, Chimneys, or Skerries
Order of stability of minerals under weathering:
What are the soil horizons?
What is the O-horizon
Describe O-Horizon in humid, semi arid, and arid environments
Humid - O-horizon has thick accumulations of plant matter
Describe A-Horizon:
Humid
Semi arid
Arid
Humid - has a very thick zone of eluviation resulting in nutrients for plants
Semi Arid - moderately thick zone of eluviation. is rich in organic matter and high in soluble minerals.
Arid - a thin to nonexistent zone of eluviation. More coarse textured because of little precipitation. Soluble salts can precipitate from the water and accumulate in the soil.
What is the A - Horizon
What is the B-Horizon?
Describe the B-Horizon in environments:
Humid
Semi Arid
Arid
What is the C-Horizon?
Describe C-Horizon in these environments:
Humid
Semi Arid
Arid
Humid - it is very deep
Semi Arid - it is moderately deep
Arid - It is very near the surface and relatively intact
Till Plain
Also called ground moraine, deposition by an ice cap of glacial till forming a relatively flat to undulating surface which covers an extensive area and buries preglacial topography.
Ice-scoured Plain
An assemblage of erosional landforms on exposed bedrock resulting from the flow of an ice cap. It exhibits many of the same surficial features that are found in areas of alpine glaciation like: striations, grooves, and polished surfaces, as well as the development of roche moutonées or mammillated surfaces.
Roche Moutonée
An elongated bedrock knob which is oriented parallel to the direction of glacial flow and has a smooth rounded upstream end and usually a steep rough downstream end where the glacier plucked out the rock as it moved away.
Streamlined topography (mammillated surface)
A series of smooth rounded erosional rock mounds alternating with parallel valleys resulting from the smoothing off of a mountainous region by the ice cap.
Knob & Basin Topography
Also called knob and kette topography.
A hummocky landscape consisting of knols or mounds of glacial drift in an area interspersed with basins or kettles. Basins often contain water.
