Curt Teichert

Australia and Gondwanaland

Along the western margin of the Australian continent there exist four major sedimentary basins, filled with predominantly marine rocks from Cambrian to Tertiary in age, and up to 40,000 feet thick. Seaward these basins continue into depressions recognizable in the continental shelf and even the continental slope. Their very presence, the nature of their sediments and the composition and relationships of their fossil faunas indicate the existence of an open ocean to the west of Australia since early Paleozoic time. Composition of the Australian fossil land vertebrate faunas suggests isolation of the Australian continent since at least Permian time.

Fossile Riffe als Klimazeugen in Australien

SummaryFirst true coral reefs in Australia appear in the Silurian of northern Queensland. The reef belt then advances to the south and reaches its maximum in the Middle Devonian. In the Upper Devonian and Lower Carboniferous reef-building activity is again restricted to the north. Reefs are unknown from the Upper Carboniferous until the middle Tertiary. The southern limit of the reef belt advances along the west coast, possibly since the Miocene and reaches its extreme southerly position (32° S. lat.) in the late Pleistocene, probably the last Interglacial. Since then it has moved northward to 29° N. lat. In the east the Great Barrier Reef reaches southward as far as 24° N. lat. and no more southerly reefs of Pleistocene or Recent age are known. The significance of these facts for the theory of continental drift is difficult to assess. The Pleospongia („Archaeocyathinae“) of the Cambrian are not reef-builders and their distribution could be satisfactorily explained by assuming that they were restricted to the temperate belts in both hemispheres. Conditions in the Middle Devonian with their extraordinary expansion of reef-building organisms require special explanation, but before a shift of the Australian continent relative to the climatic belts is accepted, it is neccessary to study the very irregular course of the limits of the present reef belt. Comparing marine faunas of similar latitudes today one may encounter differences perhaps not less profound than those between Devonian faunas in comparable belts.

Die Klufttektonik der cambro-silurischen Schichtentafel Estlands

ZusammenfassungDie cambro-silurische Schichtentafel von Estland zeigt zwei Kluftsysteme: das eine mit Klüften in NW-SO- und NO-SW-Richtung, das andere mit solchen in N-S- und O-W-Richtung. Das erste ist das ältere und seine Anlage dürfte in der Zeit der jungkaledonischen Faltung zu suchen sein, zu der auch die Einmuldung der Schichtentafel erfolgte. Zur Zeit der varistischen Faltung erfuhren diese Richtungen eine erneute Betonung. Das zweite Kluftsystem dürfte jüngeren, tertiären Alters sein. In diese Zeit, wahrscheinlich in noch jüngere Zeitabschnitte gehören dann auch die Brüche, die die Estländische Tafel heute begrenzen.