WEAVER: INVERTEBRATE PALEONTOLOGY AND HISTORICAL GEOLOGY 721 



glaciation began in the Lower Carboniferous, continued into the Upper, and was 

 accentuated in the Permian. In Kashmir the Gangamopteris flora is interbedded 

 with strata equivalent to the Productus limestone. Knowlton considered that 

 this flora originated either in Australia or Antarctica and, with the advance of 

 the ice age, was dispersed northward throughout the southern hemisphere but 

 was prevented from reaching the northern areas by the transverse sea which 

 connected Tethys Basin with the Caribbean Sea and also by the prevailing aridity 

 of northern lands. 



Prior to 1900 the term Permo-Carboniferous was used widely in North 

 America for sediments now referred to in part as Permian; as early as 1859 it 

 was employed by Meek and Hayden for deposits in Kansas. In 1917 J. A. Udden 

 made known in the Marathon area of western Texas a section of 6,000 feet of 

 dolomites and limestone deposited during the Permian in a sea which occupied 

 large areas of Texas, Kansas, and Oklahoma. This sea was limited on the west 

 by the ancestral Eocky Mountains and on the southeast by the Llanorian uplift. 

 From these lands and from the Arbuckle and Wichita uplifts came the sediments 

 of this age, which are to a considerable extent red beds. Important contribu- 

 tions have been made to the study of these formations by Philip King, of the 

 U. S. Geological Survey. In eastern North America the Paleozoic Appalachian 

 trough was drained and the thick accumulation of sediments folded, faulted, and 

 elevated into the Appalachian IMountains at this time. 



Triassic: The threefold classification of Triassic rocks of central Germany 

 as the Bunter sandstone, Muschelkalk, and Keuper had been established prior 

 to 1850, largely through the investigations of Alberti. Later each of these divi- 

 sions was subdivided into groups with names based on local variations of lith- 

 ology. The middle marine Muschelkalk member decreases in thickness westward 

 and in England its equivalent, together with the Bunter and Keuper, forms a 

 sequence of continental sandstones, shales, conglomerates, and local beds of gyp- 

 sum and rock salt, which were named the New Red Sandstone. The north Ger- 

 man Triassic became the standard for comparison with the Alpine areas dur- 

 ing the second half of the last century. 



The threefold division in Germany is not characteristic of the Alpine region, 

 where folded and faulted fossiliferous marine limestones, dolomites, and shales 

 form rugged outcrops extending from Austria westward to the Jura Mountains. 

 Several important monographs on the stratigraphy and faunas of these rocks 

 had been published before the middle of the past century by Lill, H. G. Bronn, 

 Klipstein, Emmrich, Hauer, and von Buch. As a result a partial correlation of 

 the Alpine Triassic with that of northern Germany was made by a comparison 

 of distinctive faunal assemblages. In 1858 F. Hauer, of the Austrian Geological 

 Survey, divided the Triassic succession in the Venetian Alps into seven groups 

 on the basis of the' paleontological sequence. Von Richthof en in 1860 published a 

 work on the Triassic of the South Tyrol, with a full description of the areal dis- 

 tribution, lithology, and tectonic structure of the different formations, and made 

 the suggestion that the limestones of the Southern Alps had been formed by the 

 slow subsidence of reef-building corals. Investigations of the Bavarian Alps by 

 Oppel in 1859 and Giimbel in 1861 led to the recognition of the Dachstein lime- 

 stone and the Kossen formation as the Rhaetic group of the uppermost Triassic. 

 Giimbel, while director of the Bavarian Geological Survey, studied the Alpine 



