Conglomerate

A conglomerate is a type of sedimentary rock formed from rounded rock fragments or pebbles that are cemented together by a finer-grained matrix, such as sand or silt.

The rock fragments can be composed of different minerals and rocks – the easiest way to imagine a conglomerate is to imagine a man-made conglomerate: a block of cement with old bricks, glass, and other mill waste mixed in.