How do the processes of weathering and erosion shape earths surface?

Answer 1

Solar ultraviolet radiation breaks chemical bonds, degrading material. There is also mechanical wear from thermal expansion and contraction caused by the diurnal cycle. At night material cools and contracts, during the day it warms and expands. Over time this causes rock to crack and break.

Faster yet is the action of moisture. Water seeping into cracks which subsequently freezes widens gaps, pushing rock down slope. Rain and flooding carries this material downstream, eventually dumping it into the ocean. Mountains are gradually weathered down by wind born material, rain and snow.

These processes result in erosial features such as sand bars, gravel beds, gullies, and canyons. Young canyons are typically fairly steep and straight. Older canyons will be broad, and the rivers flowing through them eventually meander, creating big loops known as "ox bows." Solitary rock formations on a broad flood plain or "peneplain" that survive long term riparian activity are known as "monadnocks."