Question

1. how can glacial striations (scratches) tell you the direction the glacier moved?

valleys
in mountainous or hilly terrain, advancing glaciers seek the lowest passages and move through valleys first. stream valleys often have a v - shape in profile, especially in mountain areas. streams and the sediment they carry occupy only the bottom of the valley and do not erode the sides of the valley. the sides of a stream valley in mountainous terrain collapse under the influence of weathering and gravity, which often give them a steep but uniform slope of the v - profile. when a glacier moves down a mountain valley filling it with ice, the erosive action of the glacier and its load of sediment pluck, scrape, and scour the sides of the valley changing its profile to a broader u - shape. u - shaped valleys are strong evidence of glacial erosion.

1. why do rivers create v - shaped valleys while glaciers create u - shaped valleys?

how can we recognize deposition caused by glaciers?
sediment transported by glaciers must also be deposited. there are several differences between sediments deposited by ice and sediments deposited by water or wind. water and wind sort sediments. moving ice transports and deposits sediment without regard to particle sizes. therefore, sediments deposited directly by glaciers are unsorted and do not show layering. this unsorted glacial debris is sometimes called till. stream sediments are deposited where streams flow, usually in the bottom of a valley. but a glacier can move its debris anywhere that the ice covers, even to the highest parts of new york state. glacial sediments often cover the whole land surface with an uneven blanket of till composed of mixed particle sizes. water and wind usually

Explanation:

Glacial striations are scratches made by rocks embedded in the glacier's base. As the glacier moves, these rocks scrape along the bedrock. The direction of the scratches (striations) indicates the direction of the glacier's movement. For the valley - shape question, rivers erode mainly through the bottom (vertical erosion in the early stages) creating a V - shape. Streams and their sediments occupy only the bottom. Glaciers, with their large mass and the action of plucking (removing rocks from the valley sides) and abrasion (scraping), erode the sides as well as the bottom of the valley. This lateral (side - to - side) and vertical erosion widens and deepens the valley, creating a U - shape.

Answer:

1. The direction of glacial striations (scratches) is parallel to the direction of the glacier's movement.
2. Rivers create V - shaped valleys because they mainly erode the bottom of the valley (vertical erosion in the early stages) and their sediments occupy only the bottom. Glaciers create U - shaped valleys because they erode both the sides (by plucking and abrasion) and the bottom of the valley, widening and deepening it.