The Hicks Dome is underlain by ultramafic igneous rocks and igneous diatremes or breccia pipes. Volcanic rocks of Honolulu Volcanics include agglomerates, breccia, breccia-tuffs, scoria bombs and tuffs. Diatreme-facies kimberlite is more properly called an ultramafic breccia rather than a tuff. Turbidites occur as fine-grained peripheral deposits to sedimentary breccia flows. Santa Rosa Island Volcanics consist mainly of basaltic breccia, which erupted about 19 Ma. Occasionally, metamorphic rocks can be brecciated via hydrothermal fluids, forming a hydrofracture breccia. Below these layers lie more than of andesite glass and breccia. Two types of rocks were found in the geological samples&colon; basalt and breccia. Thick sequences of sedimentary (colluvial) breccia are generally formed next to fault scarps in grabens. The geology consists of a dark breccia of gabbros and dolerites intruding Archaean gneiss. His name appears in inscriptions on vessels made of schist, alabaster, breccia and marble. His name appears in inscriptions on vessels made of schist, alabaster, breccia, and marble. Five rock types have been identified&colon; sandstone, granite, conglomerate, limestone and breccia. The volcano is a sill composed of layers of volcanic ash and breccia. A thick fault breccia separates it from the overlying Qomolangma Formation.