Glaciers & Wind

1. Glaciers & Wind Chapter 23 Section 4 • Abbie & Jaylea

2. How Glaciers Form and Move • Glaciers form in places where snow falls than melts or sublimates. • There are two types of glaciers: continental and valley glaciers. • A continental glacier is a tick sheet of ice that covers a huge area such as a continent or a large island. • A valley glacier is a glacier that occurs in a high mountain valley.

3. Glacial Erosion and Deposition • In Plucking a glacial ice widens cracks in bedrock beneath the glacier. • Glaciers cause many distinctive features in the landscape, including cirques, horns, U-shaped valleys and glacial lakes. • Cirques look as if they were made by a giant ice cream scoop. If several cirques form close together, a ridge may be left between them. • When rides connect together they form a pyramid shaped peak called a horn. • When glaciers flow though V-shaped valleys cut by running water they widen them into U-shaped valleys. • Glacial valleys are U-shaped because the moving ice scours the entire valley, eroding rick from the valleys bottom and sides

4. U-shaped Glacier

5. Plucking

6. Most of Earths fresh water is frozen in the continental glacier that cover Antarctica and Greenland. • A valley glacier usually begins near a mountain peak and winds down through a valley formed originally by a stream. • The force of gravity pulls the ice down hill. • Like a river, a glacier flows fastest in the middle and slowest along the sides.

7. Features Formed by Glacial Deposition • When a glacier melts, it deposits its load of sediment, creating a variety of landforms. • Glacial sediment is called till. Till is an unsorted mixtures of sediment that has many fragments of many sizes. • The till forms moraines, mounds of sediment at the downhill end of the glacier and alone it sides.

8. Wind Erosion and Deposition • The speed of wind determines the side of the materials it carriers. • Slower winds carry small particles, like dust. • Faster winds have more energy and can life larger particles, such as sand. • Most wind erosion occurs in the dry areas of the world such as the deserts. Wind erosion also occurs in areas where drought has caused the ground to dry out and the soil is not held in place by plants

9. How wind causes Erosion • In saltation, wind lifts sand grains a short distance into the air. • Wind erodes the land by deflation and abrasion. • The process of deflation occurs when wind picks up and carries away loose surface material. • Abrasion is a type of mechanical weathering.

10. Effects of wind Deposition • Features deposited by wind include sand dunes and loess deposits. • Deposits formed from windblown sand are called dunes. • Loess deposits formed from windblown dust are called loess. • The two major sources of loess are deserts and glacial deposits. A dust storm can transport tons of dust for long distances. • Dust from the Sahara Desert in Africa regularly blows across the Atlantic Ocean