Conglomerate

Conglomerate, or PLUMPUDDING-STONE, a rock consisting of various-sized, round, water-worn stones cemented together, the binding material being generally of a calcareous, siliceous, or ferruginous character. Now and again the stones are held together by simple compression without any cement. Conglomerate is evidently gravel compacted into a more or less coherent mass. Like coarse gravel and shingle, some conglomerates are very tumultuous in appearance, and show no lines or planes of deposition. Generally, however, rocks of this kind exhibit rudely alternating layers of finer and coarser materials. The included stones may consist of any kind of rock or mineral, but the harder species, such as quartz-rock and quartz, are apt to preponderate. Conglomerates are generally beach-deposits, either marine or lacustrine; sometimes they are of fluviatile origin.