Alluvial Fans and River Systems

The video explores the journey of sediments from mountain flanks to the sea, focusing on the dynamics of sediment transport and deposition. It discusses the role of precipitation in sediment movement, the development of river systems, and the formation of alluvial fans. The video highlights the changes in sediment characteristics and the challenges of exploiting sediment reservoirs.

What is the final destination of sediments transported from the mountains?

• The forest

• The sea

• The lake

• The desert

How does heavy precipitation affect water flow in mountain valleys?

• It has no effect on water flow

• It decreases water velocity

• It increases water velocity

• It causes water to evaporate

What happens to sediments on mountain slopes during normal precipitation?

• They are all washed away

• They remain untouched

• They are partially carried away

• They are compacted into rocks

What characterizes the river system in wider valleys?

• No channels at all

• A circular channel system

• A network of anastomosing channels

• A single straight channel

During quiet moments, what happens to the sediments in the river system?

• They are all carried away

• They are transformed into fossils

• Some are carried away, some are left behind

• They are all deposited

What major change occurs when rivers exit steep mountains?

• The river becomes narrower

• The river becomes a waterfall

• The river slope decreases

• The river dries up

What is the shape of an alluvial fan?

• Circular

• Rectangular

• Triangular

• Hexagonal

Where is the apex of an alluvial fan located?

• At the center of the fan

• At the exit of the valley

• In the middle of the plain

• At the base of the mountain

How does grain size change from the apex to the foot of an alluvial fan?

• It becomes finer

• It becomes coarser

• It becomes more mixed

• It remains the same

Why are alluvial fans important in sedimentary systems?

• They are rare geological features

• They have low permeability

• They are difficult to access

• They have large permeability