in size), but it is distinguished from conglomerate because the rock fragments have sharp edges that have not been worn down. These indicate that the gravel was deposited very close to its source area, since otherwise the edges would have been rounded during transport. Most of the rounding of rock fragments takes place within the first few kilometers of transport, though complete rounding of pebbles of very hard rock may take up to 300 km of river transport.

A megabreccia is a breccia