278 THE CLIMATIC FACTOR AS ILLUSTRATED IN ARID AMERICA. 



and shortly after early Coal Measures time. With the sharks also vanished most of the 

 crinids, but otherwise there was an abundance and variety of marine life (wide distribution 

 of large foraminifers) with much limestone formation. The vanishing of the sharks does not 

 appear therefore to have been due solely to a reduction of temperature, but may have been 

 further helped by the oscillatory condition and retreat of the late Lower Carbonic seas. 



Toward the close of the Lower Carbonic, or after the Culm and its coals of western 

 Europe had been laid down, mountain movements on a great scale began to take place in 

 central Europe, and then were born the Paleozoic Alps of that continent. These mountains, 

 Kayser tells us, were in constant motion but with decreasing intensity throughout the 

 Upper Carbonic, culminating in "a mighty chain of folded mountains." Toward the 

 close of the Upper Carbonic began the rise of the Urals, which was finished in late Permic 

 time when the Paleozoic Alps of Europe were again in motion. These movements are 

 also traceable in Armenia and others are known in central and eastern Asia. Likewise, in 

 America, the southern Appalachians were in movement at the close of the Lower Carbonic, 

 but the greatest of all of the Upper Carbonic thrustings began to take place at the close of the 

 period and culminated apparently in the earUer half of Permic time, when the entire Appa- 

 lachian system from Newfoundland to Alabama, and the Ouachita Mountains, extending 

 through Arkansas and Oklahoma, arose as majestic ranges anywhere from 3 to 4 miles high. 



These mountain-making movements of long duration at first caused the oceans to 

 oscillate frequently back and forth over parts of the continents, and great brackish-water 

 marshes were developed, producing the greatest marsh floras and the greatest accumulations 

 of good coals that the world has had. The paleobotanists Wliite and Knowlton tell us 

 that the climate of Upper Carbonic time was relatively uniform and mild, even subtropical 

 in places, accompanied by high humidity extending to or into the polar circles. Plant 

 associations were then "able to pass from one high latitude to the opposite without meeting 

 an efficient climatic obstruction in the equatorial region" (1910: 760). 



The marine faunas of Upper Carbonic time were fairly uniform in development, and 

 many species had a wide distribution, although the biotas were still somewhat provincial 

 in character. Limestones or calcareous shales predominated. The large Protozoa of 

 the family Fusulinidee occurred throughout the northern hemisphere and less widely in 

 South America. They were also very common in Spitzbergen. Staff and Wedekind 

 (1910) state that the Fusuhnidse occur here in a black asphaltic calcareous rock, i. e., a 

 sapropel like those now forming in marine tropical regions, according to Potonie. The 

 water, they state, was shallow, highly charged with calcium carbonate and of a tropical 

 character, or at the very least not cooler than that of the present Mediterranean. The 

 very large insects of the Coal Measures tell the same climatic story, for Handlirsch (1908: 

 11.52) says that the cockroaches of that time were as long as a finger and the libellids as 

 long as an arm. They were "brutal robbers" and scavengers living in a tropical and 

 subtropical climate, or at the very least in a mild climate devoid of frosts. We therefore 

 conclude that after Middle Devonic time the climate of the world was as a rule uniformly 

 warm and more or less humid and that it remained so to the close of Upper Carbonic time. 



During the time of these mild and humid climates vast accumulations of carbon 

 extracted by the plants out of the atmosphere were being stored up in brackish and fresh- 

 water swamps, and even greater quantities of this element were being locked up in the 

 hmestones and calcareous shales in the seas and oceans. According to the physico-chemist 

 Arrhenius, and many geologists and paleontologists, so much loss of carbon dioxide and 

 its associated water vapor from the air must have thinned the latter greatly and thus 

 largely reduced the atmospheric blanket and retainer of the sun's heat rays. Therefore 

 they hold that these factors alone were sufficient to have brought on a glacial cUmate. 

 It may lie that this theory will not stand the test of time, but even so we have learned 

 that in Carbonic times there were earth movements on so grand a scale as to be but sUghtly 

 inferior to those of the late Tertiary that were followed by the Pleistocene glacial climate. 



