34
< Back Next > Preview Main Chapter 12 Section 3 Erosion and Deposition by Ice

Chapter 12 Section 3 Erosion and Deposition by Icedodgenms.typepad.com/files/chapter-12-section-3-glaciers.pdf · Chapter 12 Section 3 Erosion and Deposition by Ice ... • Valley

  • Upload
    lydung

  • View
    222

  • Download
    4

Embed Size (px)

Citation preview

< Back Next > Preview Main

Chapter 12 Section 3

Erosion and

Deposition by Ice

< Back Next > Preview Main

Objectives

• Explain the difference between alpine glaciers and

continental glaciers.

• Describe two ways in which glaciers move.

• Identify five landscape features formed by alpine

glaciers.

• Identify four types of moraines.

< Back Next > Preview Main

Glaciers—Rivers of Ice

• A glacier is a large mass of moving ice. They are

capable of eroding, moving, and depositing large

amounts of rock materials.

< Back Next > Preview Main

Glaciers—Rivers of Ice

• Glaciers form in areas so cold that snow stays on

the ground year-round. Because glaciers are so

massive, the pull of gravity causes them to flow

slowly, like “rivers of ice.”

< Back Next > Preview Main

Glaciers—Rivers of Ice, continued

• Alpine Glaciers form in mountainous areas. One

common type of alpine glacier is a valley glacier.

• Valley glaciers form in valleys originally created

by stream erosion. As these glaciers slowly flow

downhill, they widen and straighten the valleys into

broad U shapes.

< Back Next > Preview Main

< Back Next > Preview Main

Glaciers—Rivers of Ice, continued

• Continental Glaciers are huge, continuous masses

of ice that can spread across entire continents.

• The largest continental glacier in the world covers

almost all of Antarctica. This ice sheet is approximately

one and a half times the size of the United States, and

is more than 4,000 m thick in some places.

< Back Next > Preview Main

I C E S H E E T / C O N T I N E N TA L G L AC I E R :

( I M AG E S O F G R E E N L A N D I C E S H E E T )

< Back Next > Preview Main

< Back Next > Preview Main

• Glaciers on the Move When enough ice builds up

on a slope, the ice begins to move downhill. Thick

glaciers move faster than thin glaciers, and the

steeper the slope, the faster the glaciers will move.

• Glaciers move in two ways: sliding and flowing. A

glacier slides when its weight causes the ice at the

bottom to melt. A glacier flows as ice crystals within

the glacier slip over each other.

Glaciers—Rivers of Ice, continued

< Back Next > Preview Main

Movement of Glaciers

Click below to watch the Visual Concept.

Visual Concept

< Back Next > Preview Main

• Glacier movement is affected by climate. As the

Earth cools, glaciers grow. About 10,000 years ago,

a continental glacier covered most of North America.

Glaciers—Rivers of Ice, continued

< Back Next > Preview Main

Landforms Carved by Glaciers

• Continental glaciers and alpine glaciers produce

landscapes that are very different from one another.

• Continental glaciers smooth the landscape by

scraping and eroding features that existed before

the ice appeared.

• Alpine glaciers carve out large amounts of rock

material and create spectacular landforms.

< Back Next > Preview Main

< Back Next > Preview Main

< Back Next > Preview Main

Horn ~ residual,

isolated,

pyramid-shaped

peak, caused by

the headward

erosion of

several glaciers

< Back Next > Preview Main

Cirque ~ a hollowed-out bowl-shaped

depression at the head of a glacial valley

< Back Next > Preview Main

Arête ~ sinuous, sharp-edged ridge

< Back Next > Preview Main

Hanging valley and waterfall

< Back Next > Preview Main

Types of Glacial Deposits

• As a glacier melts, it drops all the material it is

carrying. Glacial drift is the general term used to

describe all material carried and deposited by

glaciers.

• Glacial drift is divided into two main types, till and

stratified drift.

< Back Next > Preview Main

GL ACIAL TIL L I S TYP ICAL LY U NSTRATIF IED AND UNSORTED.

< Back Next > Preview Main

GLACIAL T ILL ~ MATERIAL THAT IS DEPOSITED

DIRECTLY BY THE ICE. IT IS UNSORTED.

< Back Next > Preview Main

Types of Glacial Deposits, continued

• Till Deposits Unsorted rock material that is

deposited directly by the ice when it melts is called

till. Unsorted means that the till is made up of rock

material of different sizes.

• The most common till deposits are moraines.

Moraines generally form ridges along the edges of

glaciers.

< Back Next > Preview Main

< Back Next > Preview Main

Types of Glacial Deposits, continued

• Stratified drift is a glacial deposit that has been

sorted and layered by the action of streams or

meltwater.

< Back Next > Preview Main

STRATIFIED DRIFT

< Back Next > Preview Main

Types of Glacial Deposits, continued

• Streams carry sorted material and deposit it in front

of the glacier in a broad area called an outwash plain.

< Back Next > Preview Main

OUTWASH PLAINS

< Back Next > Preview Main

Types of Glacial Deposits, continued

• Sometimes, a block of ice is left in an outwash plain

when a glacier retreats. As the ice melts, sediment

builds up around the block of ice, forming a

depression called a kettle.

< Back Next > Preview Main

Kettle

< Back Next > Preview Main

Glacial Drift: Stratified Drift and Till

Click below to watch the Visual Concept.

Visual Concept

< Back Next > Preview Main

< Back Next > Preview Main

< Back Next > Preview Main