Lecture 16

Boulder, boulder, big and round,Tell me something, real profound.

- Johnny Hart (B.C.)

Glacial erosion

Webpage for course (daytime)

Webpage for course (nighttime)

Lab midterm scores 65 4

64 26362261360459584575525425352

494745

4039

3126

17

11

2

3

2

Ice Ages

http://www.learner.org/courses/essential/earthspace/images/show6_ice_age.jpg&imgrefurl

Geologic processes are usually slow

Mountains come up, worn down

Over millions of years

Streams take a long time to Erode transport and deposit their grains

The grains transported are small

Glaciers

Can erode larger portions of mtns

Transport and deposit the material

Over 10,000s years

Grains can be the size of trucks

Ice Ages

Water

High viscosity – flows around obstructions

Ice

Flows slowly – bulldozer effect

Two general kinds (scales) of glaciation

Alpine

Continental

Snow

Accumulates in mtns

colder weather – advanceswarmer weather - retreats

Flows to lowlands

In mountains – erosion on large scale

Glacial quarrying (plucking)

AbrasionAvalanching

Glacial plucking

Abrasion

Cirques

http://www.goldengatephoto.com/westus/greatbasin.html&usg

Where several cirques meet - horn

Aretes and Cols

In valleys – transportation on large scale

Glacial vs. Stream

U-shape

Less sinuousHUGEHanging waterfalls

Lets look at some photos