Volcanic plateau up by foundering of the Earth's crust to form the present ocean basin. The Earth features numerous subaerial and submarine volcanic plateaus such as the Columbia River Plateau (subaerial) and the vast Ontong Java Plateau (submarine). Pyroclastic plateaus are produced by massive pyroclastic flows and they are underlain by pyroclastic rocks: agglomerates, tephra, volcanic ashes cemented into tuffs, mafic or felsic. Examples include Shirasu-Daichi which covers almost all of Southern Kyūshū, Japan and the North Island Volcanic Plateau in New Zealand. Volcanic plateau A volcanic plateau is a plateau produced by volcanic activity. There are two main types: lava plateaus
Craton craton. Earth's surface was probably broken up into many small plates with volcanic islands and arcs in great abundance. Small protocontinents (cratons) formed as crustal rock was melted and remelted by hot spots and recycled in subduction zones. There were no large continents in the early Archean, and small protocontinents were probably the norm in the Mesoarchean because they were prevented from coalescing into larger units by the high rate of geologic activity. These felsic protocontinents (cratons) probably formed at hot spots from a variety of sources: mafic magma melting more felsic rocks, partial melting of mafic rock, and from