Conglomerate (pronounced: con-glom-er-ate)

Conglomerate consists mostly of gravel. The particles may vary largely in size within any one sample. This variety of size is called poor sorting where the rock may consist of rocks as large as boulders as well as pieces as small as a single pea.

The particles are usually large enough that it is easy to identify the individual rock types. This information may be very helpful in identifying the source area of the conglomerate.

Conglomerates usually have large openings between the gravel particles which is filled by some groundmass such as sand or mud.

Information provided by Patrick M. Colgan, Northeastern University
http://www.casdn.neu.edu