Q.5) Distinguish between :
1 ) Attrition and Abrasion
2) U shaped valley and V shaped valley
3) Stalactite and stalagmite
4) Tributaries and distributaries
Answers
1) Attrition is the disintegration of rock due to rock particles and other materials bumping into each other, the sea bed and the coast. This eventually leads to sand formation.
Abrasion is the disintegration of rock due to rock particles scraping along the sea bed, causing a sandpaper effect. This can eventually wear away a cliff.
2) A U-shaped valley has very steep sides and a wider valley floor than the V-shaped valley. These usually form by one of the three processes:
- Rapid vertical river erosion
- The collapse of a system of underground caves
- Tectonic movement
A V-shaped valley forms mainly due to glacial erosion. It has relatively steep sides and a very narrow valley floor (1-5 metres).
3) A stalactite hangs from the roof of a cave. It is formed from frozen lava, minerals, mud, peat, pitch, sand, sinter, or amberat (one of these).
A stalagmite starts from the floor and rises from the floor. Its materials compose of the same materials as a stalactite. If the stalactite and the stalagmite connect, they form a pillar.
4) Tributaries refer to those smaller rivers (though not necessarily) coming out from the main river channels.
Distributaries are a branch of a river that does not return to the main stream after leaving it (as in a delta).