Antarctica in Retrospect
Antarctica is a place that does not give up her secrets easily. A casual observer might be impressed by the natural beauty of the landscape or by the brutally cold climate, depending on the weather at the time. Geologists who come to study the Transantarctic Mountains are initially overwhelmed by the Niagara of information that confronts them. This is true of mountainsides of exposed granitic gneisses of the Granite Harbor Intrusives, of whole mountain ranges composed of flat-lying sedimentary rocks of the Beacon Supergroup which attains a thickness of 3 km, not to mention the profusion of massive sills of Ferrar Dolerite that intruded the sedimentary rocks, and the thick plateaus of Kirkpatrick Basalt that was poured out onto the eroding surface of the Beacon rocks. How did all these rocks form on the edge of the East Antarctic craton? Whatever geological activity is recorded by the rocks of the Transantarctic Mountains took place in a tectonic setting of continental rifting, compressive subduction, and amalgamation of continental fragments, all of which occurred during 585 million years of geologic time between 750 and 165 Ma.