More ErosionMore Erosion

Or . . . you’re really wearing me Or . . . you’re really wearing me down.down.

Wind ErosionWind Erosion

Wind can be a significant agent of Wind can be a significant agent of erosion in beach areas, deserts and erosion in beach areas, deserts and semi-arid regions such as the U.S. semi-arid regions such as the U.S. Southwest.Southwest.

In both beach and desert areas, wind can In both beach and desert areas, wind can move sand into large dunes.move sand into large dunes.

Barchan DuneBarchan Dune

Wind lifting loose Wind lifting loose material (deflation) material (deflation) from desert floors from desert floors creates desert creates desert pavementpavement

Desert pavement is a Desert pavement is a surface of coarse surface of coarse pebbles and cobbles.pebbles and cobbles.

Road RunnerRoad Runner

Wind blown sand (sandblasting) can scour Wind blown sand (sandblasting) can scour rock formations into interesting shapes.rock formations into interesting shapes.

Wind can blow away precious topsoil from farm Wind can blow away precious topsoil from farm land. As shown in this picture from the Dust Bowl land. As shown in this picture from the Dust Bowl ca. 1932.ca. 1932.

GlaciersGlaciers Two kindsTwo kinds

Ice Sheets or Ice Sheets or Continental GlaciersContinental Glaciers

Valley or Alpine Valley or Alpine GlaciersGlaciers

A continental A continental glacier called the glacier called the Laurentide Ice Laurentide Ice Sheet covered most Sheet covered most of NYS during the of NYS during the last ice age.last ice age.

Alpine or Valley Glaciers cover a Alpine or Valley Glaciers cover a much smaller area. Sometimes only a much smaller area. Sometimes only a valley.valley.

Glaciers push sediments out front (end or Glaciers push sediments out front (end or terminal moraine) and drag it along the terminal moraine) and drag it along the sides (lateral moraine)sides (lateral moraine)

A glacier’s movement downhill is A glacier’s movement downhill is due to it’s own weight and due to it’s own weight and gravity.gravity.

If more snow and ice accumulates If more snow and ice accumulates than melts, a glacier will advance.than melts, a glacier will advance.

A glacier’s movement is similar to A glacier’s movement is similar to a stream in that its middle moves a stream in that its middle moves fastest and the sides and bottom fastest and the sides and bottom more slowly. more slowly.

A glacier’s weight and sediments beneath A glacier’s weight and sediments beneath it carve deep parallel grooves and it carve deep parallel grooves and scratches into bedrock called scratches into bedrock called striations.striations.

The direction of these striations shows the The direction of these striations shows the direction of former glacial movement.direction of former glacial movement.

Evidence of Glaciation

Striations

Ayers Rock, Australia

The wide, thick ice of a glacier erodes the The wide, thick ice of a glacier erodes the valley walls as much as the rock beneath valley walls as much as the rock beneath it thereby forming a it thereby forming a U-shaped valleyU-shaped valley..

U-Shaped Valleys

Glaciers can move sediments for miles. When Glaciers can move sediments for miles. When they melt they often leave they melt they often leave boulders that are boulders that are a different type of rock from the bedrock a different type of rock from the bedrock beneath thembeneath them. These are called . These are called eraticseratics..

Eratics

UnsortedUnsorted SedimentsSediments Glaciers mix sediments of all sizes and Glaciers mix sediments of all sizes and

shapes. The sediment deposits are shapes. The sediment deposits are unsortedunsorted..

The Finger LakesThe Finger Lakes

The Finger Lakes consist of 11 The Finger Lakes consist of 11 long, narrow, roughly parallel long, narrow, roughly parallel lakes, oriented north-south as lakes, oriented north-south as fingers of a pair of outstretched fingers of a pair of outstretched hands. The southern ends have hands. The southern ends have high walls, cut by steep gorges. high walls, cut by steep gorges. These lakes all formed over the These lakes all formed over the last two million years by glacial last two million years by glacial carving of old stream valleys. carving of old stream valleys. The deepest of which is Seneca The deepest of which is Seneca at 618 feet.at 618 feet.

Glacial Features - CirquesGlacial Features - Cirques

Glacial Features - HornGlacial Features - Horn

Glacial Features - DrumlinGlacial Features - Drumlin

Glacial Deposit - EskerGlacial Deposit - Esker

Glacial Feature – Kettle LakeGlacial Feature – Kettle Lake