What is the role gravel

stone gravel refers weathered rock by the water flow from the long-term particle transport is non-angular natural aggregates of 2 ~ 60mm.Sediments classification in one name. Often the symbol G represents. It refers to the average particle size greater than 1 mm of rock or mineral debris. Average particle size, can be broken down into the gravel, boulders, coarse gravel and fine gravel are three: the average particle size of 1-10 mm, called fine gravel; 10-100 mm, called coarse gravel; greater than 100 mm , called boulders. Gravel after cementation diagenesis, called conglomerate or breccia.stones for driveway of the stones in the road, the road is more robust.
Gravel from the exposed surface of the rocks formed through weathering; often deposited in the foothills and piedmont; or due to water erosion after being crushed rock to produce after fluvial deposition; after forming a conglomerate or breccia cemented gravel.