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Review

Karst and Hydrothermal Processes: underground water

1. Karst Processes and Landscapes

1a. Solution and Precipitation

1b. Caverns and Related Features

1c. Karst Topography

Maps: Mammoth Cave, KY and Lake Wales, FL

2. Hydrothermal Features

2a. Hot Springs

2b. Geysers

2c. Fumaroles

Next: Deserts and Glaciers: dry and ice...

• Fluvial and Aeolian Processes in Dry Regions of the World and related landforms

• Glacial Processes and related landforms

Desert Landforms

McKnight 8.19: Dry climates

Regions of the world where water is scarce but water is still important and plays a large role in shaping landforms

Desert landforms: processes which shape them are related to those that shape landforms in more humid areas: but there are key differences

• Weathering: mechanical weathering dominates

  
  
  

• Creep: due to lack of water, soil creep is nearly non-existent in desert areas

  
  
  

• Soil and Regolith: thin or non-existent layer of soil

  
  
  

• Rainfall: usually in short, intense bursts

  
  
  

• Streams and Drainage

  
  
  

• Wind

  
  
  

• Drainage Basins
  McKnight 18.2: Nevada Drainage

  
  
  

  Vegetation

1. The Work of Water in Dry Regions: Fluvial Processes

• Water is the most important external landform shaping agent in dry regions

  
  
  

• WWW) Desert Landforms

1a. Surface Water in Deserts

• lakes, rivers and streams exist, but seldom have water in them

• Map: San Juan Pueblo, NM

McKnight 18.4: Nile River

• exception: exotic rivers

Humid regions: characteristics of rivers?

Desert regions: characteristics of rivers?

• arroyos, gullies, washes, coulees in N. America
  
• wadi in N. Africa/Middle East
  
• donga in S. Africa
  
• nullah in India

McKnight 18.6: Dry Lake Beds in Australia

• playas: what are they?

McKnight 18.8: Playas in Western US

• exception: Great Salt Lake

The real effect on desert landforms is from fluvial processes: flowing water

• regardless of how scarce it is

1b. Fluvial Erosion in Arid Lands

Fluvial (flowing water) processes are most important way desert landforms are shaped

McKnight 18.10: Slope in Dry and Moist Areas

• how they differ

McKnight 18.11: Bornhardt

McKnight 18.12: Australian Bornhardt

• WWW) Inselbergs in the American West

• what are they

McKnight 18.13: Pediments

• what are they

1c. Fluvial Deposition in Arid Lands

McKnight 18.14: Piedmont

Generic term for the area at the foot of a mountain range

In desert areas: zone of fluvial deposition

• characteristics

Fluvial erosion and deposition create unique desert landforms

• McKnight 18.25: Basin and Range Landscapes

• McKnight 18.29: Mesa and Scarp Landscapes

• McKnight 18.26: Basin and Range and Mesa and Scarp Landscapes

1d. Desert Fluvial Landforms: Basin and Range Terrain

Basin and range region: huge area, minimal external drainage

Raitz Landforms Map

McKnight 18.26: Basin and Range

• Ranges: origins

  
  
  

• Piedmonts: what are they

  
  

• McKnight 18.14: Piedmont cross section

  
  
  
  

• alluvial fan: how it forms

  
  

• Map: Ennis, MT

McKnight 18.27: Alluvial Fan Image

• the basin: what is it; characteristics

1e. Desert Fluvial Landforms: Mesa and Scarp Terrain

Map: San Juan Pueblo, NM

Colorado Plateau: Fluvial Systems

McKnight 18.25: Basin and Range and Mesa and Scarp Landscapes

Four-corners area of the US Southwest

• mesa = 'table' in Spanish

• scarp = short for escarpment - steep, even vertical cliffs

McKnight 18.29: Mesa and Scarp Photo

• characteristics

McKnight 18.30 Cross Section

• caprock and escarpment

McKnight 18.33: Pinnacles, Buttes, Mesas, Plateaus

• how related

Weathering and erosion: sapping

• what is it

McKnight 18.34: Badlands

• characteristics; how differ from mesa and scarp areas

2. The Work of the Wind in Dry Regions: Aeolian Processes

Wind is closely associated with deserts but plays a somewhat limited role in shaping desert landforms with the exception of sand dunes

• Aeolus: Greek god of the winds

Aeolian processes: related to the movement of air over the earth's surface

2a. Aeolian Erosion and Transportation

McKnight 18.18: Aeolian Transportation

Deflation: movement of loose particles through the air or along the ground

• suspension
  
• saltation
  
• traction

Abrasion: natural 'sandblasting'

• how does it work

2b. Aeolian Deposition

• Much is deposited in a thin layer with no distinct pattern

Sand dunes: one of the most distinctive desert landforms

McKnight 18.19: Sand Dune Movement

• how it works

McKnight 18.20: Common Dune Patterns

Barchan: usually mobile dunes on a stable (eg., non-sand) surface

• characteristics

  
  
  
  

• McKnight 18.21: A Big Barchan dune

McKnight 18.20: Common Dune Patterns

Traverse dunes: less uniform, linear dunes

• characteristics

Seifs: linear, parallel, ridges of sand

• characteristics

  
  
  
  

  McKnight 18.22: Australian Seifs

2c. Desert Aeolian Landforms

McKnight fig. 18.1: Erg

Ergs

• erg = Arabic for sand

  
  

• characteristics

  
  
  

• origin of sand

  
  
  

• Relict ergs

  
  

  Map: Burwell NW, NE

McKnight 18.3: Reg

Regs

• reg = Arabic for stone

  
  

• characteristics

  
  
  

• desert pavement, desert armor, gibber plains

Hamada

• hamada = Arabic for rock

  
  

• characteristics

Sum: Desert Landforms

1. The Work of Water in Dry Regions: Fluvial Processes

Key: despite its scarcity, water is the most important external landform shaping agent in dry regions of the world

1a. Surface Water in Deserts

• ephemeral, intermittent lakes, rivers and streams

1b. Fluvial Erosion in Arid Lands

• same fluvial processes: different effect due to lack of soil and vegetation in deserts
  
• bornhardts, inselbergs, pediments

1c. Fluvial Deposition in Arid Lands

• piedmonts: zone of fluvial deposition in deserts
  
• creates unique and distinctive landforms...

1d. Desert Fluvial Landforms: Basin and Range Terrain

• ranges, piedmonts, alluvial fans, basins

1e. Desert Fluvial Landforms: Mesa and Scarp Terrain

• pinnacles, buttes, mesas, plateaus, sapping, badlands

2. The Work of the Wind in Dry Regions: Aeolian Processes

Aeolian processes: related to the movement of air over the earth's surface

Most effective where surface material is fine, dry and not held in place by vegetation

2a. Aeolian Erosion and Transportation

• wind moves and erodes the earth's surface: deflation, abrasion

2b. Aeolian Deposition

• sand dunes: barchan, traverse, seifs

2c. Desert Aeolian Landforms

• ergs, regs, hamada

Glaciers and Glacial Landforms

McKnight 9.5: The Hydro Cycle

• Ice and landforms

  
  
  

• Ice ages

McKnight 19.1a: Pleistocene Glaciation

• Pleistocene: last great Ice Age: approximately 2 million years ago to 10,000 years ago

  
  

• characteristics

McKnight 19.1b: Pleistocene Glaciation: US Detail

• driftless area

McKnight 19.1c: Pleistocene Glaciation: Europe Detail

McKnight 19.2: Contemporary Glaciation

McKnight 19.3: Contemporary Glaciation in N. America

Focus on the effects of ice and glaciers which directly affect landforms

• but other important environmental effects:

Periglacial processes: zone beyond the extent of glaciers and ice

• effects

Sea level changes: if more water is stored as ice, there is less water in oceans

• effects

Crustal depression: weight of ice caused earth's crust to sink: up to 4000 feet

• effects

Precipitation changes: increase in precipitation particularly during glacial retreat

• effects

1. Glaciers Formation and Flow

Glaciers form when there is a year to year accumulation of snow

• why? how?

McKnight 19.8: Snow to Ice

• what happens

Glacial flow

• why and characteristics

McKnight 19.10: Glacial Flow vs Glacial Advance

Glacial ice is always flowing, even though the glacier itself may not be advancing

McKnight 19.9: Glacier Cross Section

• accumulation zone

  
  

• ablation zone

Overall result of glacial flow is a form of erosion by water

Glacial erosion accounts for only about 7% of erosion (now)

2. Mountain Glaciers

McKnight 19.5: Mountain Glaciers

• icefields

McKnight 19.6: Alpine Glaciers

• alpine glaciers

• cirque glaciers

• valley glaciers

• piedmont glaciers

McKnight 19.28: Landforms shaped by Mountain Glaciers

• hanging valleys
  
• arete
  
• horn
  
• cirques
  
• glacial trough

3. Continental Ice Sheets and Glaciers

McKnight 19.1a: Pleistocene Glaciation

• form in non-mountainous areas of continents

3a. Development and Flow of Pleistocene Glaciation

• developed in subpolar and midlatitude areas and spread outward in all directions

  
  

• initial movement was along valleys and from higher to lower areas

3b. Erosion by Ice Sheets

Glacial movement tends to smooth out the land beneath it

• broadens out valleys, flattens ridges

Effectiveness of erosion by glaciers

• depends on...

McKnight 19.16: Plucking

• how it happens

  
  
  

• roche moutonnee

McKnight 19.11: Glacial Abrasion

• grooves (bigger), striations (smaller)

  
  

  

  Glacial Grooves on Kelleys Island, Ohio (2001)

  
  

  

  Glacial Grooves on Kelleys Island, Ohio (2001)

WWW): Finger Lakes in NY

• characteristics

Results: a smooth but not flat terrain

• ice-scoured hills, scooped out depressions

• soil and smaller rock absent - bedrock at or near surface

• some deposition of material as glaciers retreated

• deranged drainage system: no pattern

Transportation by Glaciers

• What glaciers can transport

3c. Deposition by Ice Sheets and Glaciers during Pleistocene

Maps: Jackson MI, Palmyra NY






Chippewa Moraine, Wisconsin

Pleistocene glaciers

• Canada vs the US

Drift: any material moved by glaciers

Many glacial deposits are unstratified and amorphous (not particular shape)

McKnight 19.13: Till Photo

Till: material deposited directly by moving or melting ice, with no meltwater flow or redeposition involved; usually occurs at the edge of a glacier

Till plain:

• characteristics

McKnight 19.14: Erratic Photo

Erratics: huge fragments of rock, carried and deposited by glacier

Other glacial deposits do have particular patterns: stratified

Moraine: irregular rolling hills and ridges; concentrations of glacially deposited materials

McKnight 19.20: Terminal Moraine

Terminal moraine:

• what is it; characteristics

McKnight 19.18: Glacial and Glaciofluvial Features

Recessional moraine:

• what is it; characteristics

WWW) Terminal and Recessional Moraines in US Midwest

Usually shaped in concave arcs bulging outward in the direction of ice movement

McKnight 19.18: Glacial and Glaciofluvial Features

Ground moraine:

• what is it; characteristics

Drumlins: ridges aligned parallel with the direction of the ice movement

• characteristics

Glaciofluvial Features

• stratified due to sorting and deposition by running water

• typically gravel, sand, and silt - water cannot move larger particles

• glacial runoff: characteristics

McKnight 19.18: Glacial and Glaciofluvial Features

Outwash plains:

• characteristics

Eskers: long sinuous ridges of stratified drift

• characterisitcs

  
  
  

  McKnight 19.22: Eskers in Canada

McKnight 19.23: Kame

Kame: small, steep mounds or conical hills

• characteristics

McKnight 19.19: Kettles

Kettle: chunks of ice left behind as glacier melts

• characteristics

Sum: Glaciers and Glacial Landforms

• The role of ice, and in particular moving ice - glaciers - in shaping landforms

• what we can see today in the landscape is the result of existing glaciers

• ... and the most recent ice age - the Pleistocene

1. Glaciers Formation and Flow

• glaciers form when there is a year to year accumulation of snow

• new snow accumulates on top of the old snow - compacting it into ice

• gravitational forces pull ice downslope

• accumulation zones and ablation zones

Overall result of glacial flow is a form of erosion by water

• moving and shaping soil and rock particles into landforms

• scraping and polishing bedrock

2. Mountain Glaciers

• icefields, alpine glaciers, cirque glaciers, valley glaciers, piedmont glaciers

• Landforms shaped by Mountain Glaciers: hanging valleys, arete, horn, cirques, glacial trough

3. Continental Ice Sheets and Glaciers

3a. Development and Flow of Pleistocene Glaciation

3b. Erosion by Ice Sheets

• effectiveness of erosion by glaciers, plucking, roche moutonnee

• glacial abrasion: grooves (bigger), striations (smaller)

...transportation by glaciers...

3c. Deposition by Ice Sheets and Glaciers during Pleistocene

• unstratified, no patterns: drift, till, till plain

• unstratified, patterns: moraine, terminal moraine, recessional moraine, ground moraine, drumlins

• stratified, patterns due to glacial runoff: outwash plains, eskers, kame, kettles

E-mail: jbkrygier@owu.edu

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