The Cambrian and Ordovician Systems around the Pacific Basin, Part III

Abstract

The tenth chapter is dealt with the history of research in older rocks and Cambro-Ordovician of eastern North America. In last century Pre-Cambrian stratigraphy was started in Canada, while the New York System was instituted around Albany, N. Y. and later it was correlated to the European sequence. Subsequently the Cambrian and Ordovician Systems were classified in detail. Starting with the ventral anatomy of trilobites Walcott made invaluable contributions on the Cambrian geology and palaeontology, i.e. the Olenellus fauna, unique fauna the Burgess shale and so forth. His “Cambrian Fauna of China” 1913 provided a firm basis for the Cambrian of Eastern Asia.
The relation of the Cambro-Ordovician faunas of the continent to the European ones in the northern part of the Appalachian geosyncline and their distribution in the Appalachian mountains and further westerly beyond the lower Mississipy river and also in the interior lowland are briefly outlined.
These systems in the Cordilleran geosyncline is described in the eleventh chapeter. Stratigraphy in the western sites is followed by notes on the Alaskan faunas in the north which were allied to the Siberian ones at the beginning, but later to the Eastern Asiatic ones also. In the south it is a remarkable fact that the Mexicoan faunas are more related to the Andean ones than those of the United States, particularly in the early Ordovician age.
The Circum-Pacific Cambro-Ordovician belt is taken up in the final chapter. The history of this belt's history started in the Sinian period. In the early Cambrian age the eastern side belonged to the Olenellian province, but the other side constitued the Redlichia province. Subsequently, however, trilobites of the two sides became closer related to each other, although the early Upper Cambrian Kushan fauna was quite isolated. Trilobites were intimate between the two sides of the Northern Pacific and also on the southern Pacific side in the early Ordovician age. The aspect of the provinciality in the middle and late Ordovician ages is still obscure, sofar as trilobites are concerned.