Rapids

What are rapids? Rapids is a land form predominantly seen on the upper course of the river where there is little energy in the stream and thus having little erosion capability. Rapids occur when there river bed which the stream flows over is made out of an alternating band of rock. These rocks are made of different minerals and have different densities, thus they would be eroded by the water at a different pace. The many alternating bands of differential erosion causes the river bed to rise and drop erratically, and where the stream drops from a more resistant rock band to a lower resistant rock band, the change in gradient causes an increase of velocity in the stream.

The formation of rapids is highly similar to that of a waterfall but the difference lies in the ease of erosion of the rock bands as well as the amount of alternating rock bands. The formation of rapids can also be caused my numerous large boulders or rocks that stick out above the stream surface and is hardly eroded due to the insufficient energy of the stream. These boulders create much friction for the stream and bubbles are mixed into portions of the stream causing the appearance of "white water".





-ervin JH406 (16)