Also known as pudding stone, a rock consisting of various-sized,
round, water-worn stones cemented in a sedimentary
matrix. If the fragments are angular it is known as breccia.
Occasionally, the stones are held together by simple compression without
any cement. Conglomerate is gravel compacted
into a more or less coherent mass. Like coarse gravel and shingle, some
conglomerates show no lines or planes of deposition. Generally, however,
rocks of this kind exhibit roughly alternating layers of finer and coarser
materials. The included stones may consist of any kind of rock or mineral,
but harder types, such as quartz-rock and quartz
preponderate. Conglomerates are generally beach-deposits, either marine
or lacustrine; sometimes they are of fluvial origin. See also agglomerate.
Credit: U.S. Geological Survery
AND PLANETARY SCIENCE