GEOG 1401 Exam 4 Review

For Dr. Lee's online class

Glacier

Accumulation of ice affected by past/present movement.

Continental glaciers

Cover large areas.

Alpine glaciers

Found in mountainous areas.

Pleistocene

Ice ages.

Holocene

Present interglacial.

Accumulation

Gain. Snow, rain, avalanches.

Ablation

Loss. Melting, sublimation calving (results in icebergs).

Mass balance

Accounting system for gains/losses of ice.

Plucking

Ice at base melts, liquid water gets in bedrock cracks and freezes, rocks break free and get carried away by ice.

Scour

Rock particles at base erode bedrock surface.

Abrasion

Colliding particles break down. Size decreases downstream and becomes more rounded.

Cirque

At an upper Alpine glacier, plucking erodes headwall which forms an amphitheater/bowl shape.

Arête

Adjacent cirques may form a sharp ridge.

Horn

¾ cirques may form a sharp peak.

Hanging valley

After glaciers go away, tributary valleys may be at different levels.

Lateral moraine

Sediment is dropped on the side of a hill slope.

Drumlin

Streamlined hill formed under glacier, often found in groups.

Kettle

Block of ice buried by sediment. When ice melts, depression remains.

Esker

Sinuous ridge of sediment deposited by stream under ice.

Erratics

Boulders deposited far from bedrock source.

Isostatic rebound

When ice leaves, crust rises because the weight of the ice makes the crust sink.

Periglacial

Cold but not covered by ice.

Permafrost

Permanently frozen ground– most soil moisture doesn’t melt.

Patterned ground

Polygons develop on ground surface.

Tides

Sea level rises/falls twice in over 24 hours, monthly variation too.

Cause of tides

Earth’s rotation and gravitational attraction of sun and moon.

Spring tides

Sun/Moon align. Highest tides of the month. Full/new moon.

Neap tides

Sun/Earth/Moon make right angle. Lowest tides of the month. Quarter moon.

Relationship between ice ages and sea level?

Ice ages store more water on land which means there’s less water in oceans.

Submergent/Subsidence of coasts

Relative rise in sea level.

Emergent/Uplift of coasts

Tectonic uplift = relative drop in sea level.

Wind waves

Wind transfers some kinetic energy to water and a wave develops. Energy travels, water doesn’t. Only extent to a depth of about one-half wavelength.

Tsunamis

Different kind of wave caused by earthquakes, landslides, or volcanoes. Low height over deep water, very high at coast.

Factors of wave size

Wind speed, wind duration, and fetch: distance wind blows over water.

Wave breaking

In shallow water, waves deform because they lost contact with sea floor. Water falls over because it’s too steep.

Wave refraction

Bending of waves as they approach the shore.

Longshore drift

Acts like a stream and carries sand.

Beach drift

Water and sand rush up beach at an angle, return straight down.

Littoral drift

Beach drift + longshore drift =

Wave cut platforms

On cliff coast, waves hit base, eroding it into a wave-cut notch. Cliff eventually falls and retreats over time.

Marine terraces

Elevated platforms above sea level.

Erosion of headlands

Headland: Bedrock jutting out from coast, refraction makes waves hit side.

Leads to distinctive landforms like caves, arches, and stacks.

Summer beach

Season of small waves. Sand pushed back onto beach = broad beach.

Winter beach

Season of big waves. Sand eroded off beach and deposited offshore = small beach.

Spit

Sand grows out into water at coast indention.

Barrier beach

Drifting sand blocks stream mouth.

Tombolo

Spit connects mainland and island.

Human impact on beaches

Damming streams cut sediment supply to beaches.

Seawalls can cause erosion on seaward side.

Groins and jetties build up beaches but cause erosion elsewhere.

Beach nourishment: Artificially bring sand to beaches.

Barrier islands

Narrow islands parallel to mainland, protects from big waves.

Texas beaches

Relative sea level rise of 0.5-1 cm/yr.

Subsidence is about 5mm/yr.

1-2m of erosion/yr.

Fringing reef

Connected to land.

Ria coasts

Drowned stream valleys.

Fiord/Fjord coasts

Sea fills glacial valleys.

Safety factor

Measure of slope stability.

Decreasing slope resistance

Nature– streams and waves.

People– Road/house building.

Swelling clays– Can weaken hillside if they’re between rock layers.

Weathering– Frost action/salt crystal growth weakens rocks.

Removing vegetation– Roots hold soil and rock.

Increasing slope angle– due to tectonics or humans.

Increasing force

Adding weight to hillside like water in soil or buildings.

Creep

Slow movement of materials downslope.

Fall

Pieces break off and fall down.

Slide

Downslope movement along flat surfaces. Usually associated with rock layers.

Slump

Movement along a curved surface. Usually associated with thick, cohesive soils.

Flow

Materials move like a fluid.

Karst

Terrain dominated by solution processes and resulting landforms.

Solution (weathering)

Minerals dissolved in acidic water.

Rock types involved in solution

Limestone, dolostone, salt, and gypsum.

Solution sinkholes

Acidic surface water dissolves rock, depression gets bigger over time.

Collapse sinkholes

Subsurface water dissolves opening, surface ground collapses– often occurs after water table drops.

Tower karst

Sinkholes grow and merge leaving steep, remnant hills. Limestone may weather away.

Travertine deposits

Calcium carbonate features deposited in caverns.

Elastic deformation

Rock that’s stretched/compressed, but returns to original shape in reaction to stress.

Plastic deformation

Rock that takes on and keeps a new shape in reaction to stress.

Rupture

Rock breaks in reaction to stress.

Plateau

Region pushed up evenly.

Dome

One area pushed up higher than surroundings.

Basin

One area drops more than surroundings.

Folding: Anticlines

Area curves up like a hill.

Folding: Synclines

Area curves down like a valley.

Folding: Monoclines

Area is straight, curves up sharply, then evens out.

Faults: Normal

Pulling apart. Side going up moves away from side going down.

Faults: Reverse

Compression. Side going up climbs over side going down.

Faults: Transform

Horizontal movement.

Faults: Oblique

Some horizontal movement, some vertical movement.

Horsts

Valleys.

Grabens

Mountains.

Cuestas

Ridge made of resistant layers.

Caprock: Mesa

Flat topped hill made from caprock.

Caprock: Butte

Narrow mesa.

Drainage pattern: Dendritic

No structural control.

Drainage pattern: Radial

Radiates from high point.

Drainage pattern: Centripetal

Converges on low point.

Drainage pattern: Rectangular

Stream follows rock fractures.

Drainage pattern: Deranged

Poorly organized drainage.

Drainage pattern: Trellised

Main stream in valleys. Tributaries off ridges.

Batholith

Large mass of intrusive, igneous rock.

Dike

Vertical, small scale intrusion.

Sill

Horizontal, small scale intrusion.

Lava: Aa

Rough lava surface.

Lava: Pahoehoe

Smooth lava surface.

Volcanoes: Fissure

Lava flows out of a fracture in a rock.

Volcanoes: Shield

VERY large oceanic volcanoes.

Volcanoes: Composite

Large, continental volcanoes with pyroclastic explosions.