Shaping mountains
Most mountains are very old. But mountains like the Himalayas and the Rockies are young (only about 70 million years old!) These mountains have jagged peaks. Old mountains are smoother because their edges have been worn away.
Over thousands of years, rain, wind and ice wear away the hard rock.
The effect of wind, rain and ice on the rock is called erosion. Rainwater seeps inside the rock and freezes. As it does so, the water expands and eventually cracks and breaks the rock. Fierce winds also blow sand and tiny pieces of rock onto the mountain, slowly wearing it away.
Some mountain rivers are always frozen.
Rivers flow down mountains, carrying rocks and pebbles that cut into the rock. Up high, the rivers are frozen. These massive ice blocks are called glaciers. When glaciers move they crack the rock, and stones tear the mountain-sides.
Water carves out valleys as it flows down mountains to the sea.
Valleys are deep areas of land running between mountains. They are formed by the action of rivers and glaciers. Block mountains also create rift valleys (such as the Great Rift Valley in Africa) when the Earth’s plates move apart. Valleys are very fertile because minerals in the river water are deposited on the flat land.
Picture Credit : Google