Ice Ages and Glacial Processes

Study Notes

Ice Ages

If spring were not scheduled for another 10 million years, it would be an ice age, characterized by a prolonged period of cold with glaciers covering much of the earth.

Glacial Erosion and Deposition

Glaciers are huge moving mountains of ice that can directly affect the landscape in many ways.
Glacial erosion is the process of carving and shaping the land beneath a moving glacier.
As a glacier moves, it plucks up rocks and sediment, which then get stuck to its belly and go along for the ride.
These particles act like sandpaper and scratch the bedrock below, creating new landscapes.
Glacial erosion is responsible for creating glacial horns, cirques, and U-shaped valleys.
Glaciers carve out basins within bedrock that later fill with water, forming lakes.

Glacial Deposition

Glacial deposition is the settling of sediments left behind by a moving glacier.
As the melting glacier drops all of the rocks and sediments it previously picked up, it spreads debris over vast areas.
The unsorted materials moved and deposited by a glacier are known as till.
Lines of till that form at the edges of past glaciers leave behind landforms known as moraines.
Moraines form in lines and give a general idea of the boundaries and farthest point that the past glacier reached.
Drumlins are elongated hills composed of glacial till.

Indirect Effects of Ice Age Glaciers

One indirect effect is the creation of pluvial lakes, which are lakes that were at one time very large due to excessive rainfall associated with glaciation.
Pluvial lakes formed in desert areas due to changes in air flows and weather patterns caused by the presence of ice-age glaciers.
Another indirect effect is isostatic depression, which is the sinking of the earth's crust due to pressure from a heavy weight, such as glaciers.
When the glacier eventually melts, the earth's crust rebounds, similar to a mattress rebounding when the weight is removed.
Changes in sea level are also an indirect effect, resulting from the growing and melting of ice age glaciers.
During the ice ages, water that once filled oceans was turned to ice, resulting in a drop in sea level and the uncovering of large land bridges.

Description

Learn about the natural phenomenon of ice ages, their effects on the environment, and the processes of glacial erosion and deposition. Understand the impact of glaciers on the Earth's surface and the consequences of living in an ice age.