This rock is displayed in
Treasures” collection on the roofed patio of the visitor
center in the Robert Sibley Volcanic Regional
Preserve. The above caption is the same that is given on-site
(June 11, 2012).
Conglomerate is a sedimentary rock composed of water-worn rock or pebbles that are held within a finer-grained matrix of siliceous (silica-containing or silica-resembling) or argillaceous (clayey) substances.
In contrast to breccias, which contain angular fragments in their matrix, conglomerates consist of matrix-embedded rounded fragments.