Question

objective #6: describe the differences in the shape of valleys and characteristics of sediments deposited by streams and glaciers.

1. how does the shape of the valleys carved out by streams and glaciers differ?
2. how are the sediments deposited by a glacier and a stream different?

Explanation:

Question 17

Streams erode valleys through downcutting and lateral erosion, forming V - shaped valleys (narrow at the bottom, wider at the top, with steep sides in the upper reaches and more gentle slopes in the lower reaches due to meandering). Glaciers erode through plucking and abrasion, creating U - shaped valleys (wide, flat - bottomed, with steep, straight sides, as glaciers erode uniformly across the valley floor and sides).

Stream - deposited sediments (alluvium):

• Are sorted (particles are separated by size as streams deposit larger particles first in areas of lower velocity, like river deltas or floodplains, and smaller particles further along).
• Are stratified (layers of different - sized sediments are visible due to changes in stream velocity over time).
• Often have rounded particles (due to abrasion during transport in the stream).

Glacier - deposited sediments (till):

• Are unsorted (glaciers deposit all sizes of particles - from boulders to clay - at once as they melt, with no sorting by size).
• Are unstratified (no layering since deposition is not related to changes in velocity - like streams - but to glacial melting).
• Have angular particles (less abrasion during transport as glaciers carry particles in a solid - like mass, so they retain their angular shapes).

Answer:

Valleys carved by streams are typically V - shaped (narrower at the bottom, wider at the top, with slopes that can be steep in upper reaches and more gentle in lower reaches due to processes like meandering). Valleys carved by glaciers are U - shaped (wide, flat - bottomed, with steep, straight sides, formed by the uniform erosion of glaciers through plucking and abrasion).

Question 18