Antarctica consists of large and wholly continental east Antarctica and smaller west Antarctica, which would form islands if the ice cap were melted. Most of east Antarctica is a Precambrian Shield, in much of which charnockites are characteristic. The high Transantarctic Mountains largely follow a geosyncline of Upper Precambrian, and intruded by granitic rocks during Late Cambrian or Early Ordovician time. The rocks were peneplained, then covered by sediment which were intruded by Jurassic diabase sheets and overlain by plateau-forming tholeiites. Late Cenozoic doming and block faulting have raised the present mountains. Northeastern Victoria Land preserves part of a Middle Paleozoic orogeny. Interior west Antarctica is composed of miogeosyncliclastic and subordinate carbonate rocks that span the Paleozoic era and were deformed metamorphosed at generally low grade, and intruded by granite rocks during early Mesozoic time and possibly other times. The Antarctic Peninsula consists of metavolcanic and metasedimentary rocks intruded by Late Cretaceous quartz diorite.