Earth ScienceEarth Science

Chapter 5: Section 2Chapter 5: Section 2

Surface Processes and Surface Processes and LandscapesLandscapes

Introduction to OceansIntroduction to Oceans

• Currents are made by wind & density diffs.

• Currents distribute Earth’s solar energy.– Carry heat energy from lower latitudes to

higher latitudes & cold water to lower latitudes

• Erosion and deposition by wave action cause changes in shoreline features like beaches, sandbars, and barrier islands.– Wave action rounds sediments by abrasion.

Ocean CurrentsOcean Currents

Erosion and Deposition by Erosion and Deposition by Wave ActionWave Action

• http://www.utexas.edu/depts/grg/hudson/grg301c/hudson_grg_301c/schedule/4_water_geomorph_images/17_coastal/1.htm

Ocean CurrentsOcean Currents

• Tsunamis – large waves caused by submarine landslides or volcanic eruptions– Wavelengths can be 100 miles long– Heights can reach 100 feet

• Indonesian Tsunami of December 26, 2004– Ruptured over a length of at least 250 miles– Traveled at about 1.2 miles per second – Wave heights greater than 30 feet

Ocean CurrentsOcean Currents

Ocean CurrentsOcean Currents

Ocean CurrentsOcean Currents

Ocean CurrentsOcean Currents

GlaciersGlaciers

• Two types of glaciers:– Valley (alpine) glaciers - confined to a valley

and flows from higher to lower elevations.• Most present day glaciers are valley

glaciers.– Continental ice sheets - thick mass of ice that

covers over 50,000 square kilometers of land.• Only two exist today

–Antarctica and Greenland

GlaciersGlaciers

Glacial ErosionGlacial Erosion

• Glaciers move down slope under the influence of gravity and their own weight.– Steeper the slope the faster the movement.– When a glacier melts faster than it moves

downslope it moves backward (recedes)

• When a glacier slides over rock, the rock beneath the glacier is abraded.– Sharp corners of rocks dragged along make

long parallel scratches (striations).

GlaciersGlaciers

Glacial ErosionGlacial Erosion

• Glaciers carve U-shaped valleys– Hanging valleys form from tributaries

• Cirque– Bowl shaped erosional scar

• Horn– Sharp peak remaining from 3 or more cirques

• Arete– Ridge remaining from 2 cirques

Glacial ErosionGlacial Erosion

Glacial ErosionGlacial Erosion

Glacial DepositionGlacial Deposition

• Till – Unsorted rock deposited directly by a glacier.

• Outwash– Rock material deposited directly from the

meltwater of the glacier.

• Erratic– Large rock that is different from rock beneath

Glacial DepositionGlacial Deposition

• Moraine– Mass of glacial till left behind after a glacier

has melted.• Terminal moraine – farthest advance of

glaciers• Recessional moraine – built up where the

glacier recedes for a while, then becomes stationary

• Lateral moraine – pile of till along sides

Glacial DepositionGlacial Deposition

• Drumlin – elongated hills formed from a glacier passing over old ground moraine

• Outwash plain – sorted deposits carried by meltwater of glacier

• Kames – short, steep-sided hills of outwash• Kettle hole – formed from ice block that melts

– Many are filled with water creating deep lakes• Esker – sinuous deposits from rivers of meltwater

Glacial DepositionGlacial Deposition

Glacial DepositionGlacial Deposition

Glacial DepositionGlacial Deposition

Glacial DepositionGlacial Deposition

Wind ActionWind Action

• A dune is a mound or ridge of sand deposited by the wind.– As the wind rises up the long side of the dune,

the wind speed increases, therefore its carrying power increases (erosion increases).

– As the wind moves over the top of the dune and spreads out, its wind speed and carrying power decreases (deposition increases).

Wind ActionWind Action

Landscape Development and Landscape Development and Environmental ChangeEnvironmental Change

Landscape DevelopmentLandscape Development

• Forces that raise Earth’s surface are called uplifting forces

• Forces that lower the elevation of Earth’s surface are called leveling forces

• Climatic changes effect landscapes– The drier the climate the more angular the

landscape

• Bedrock patterns influence landscape

Stream Drainage PatternsStream Drainage Patterns

TimeTime

• Landscapes pass through stages over time– Young

• Erosion is beginning• Steep fast-moving streams & v-shaped valleys

– Mature• Low rounded hills and broad flat valleys• Streams stop eroding downward & start sidecutting

– Old• Uplands have been eroded almost to sea level• Poor drainage, small gradient, many meanders