CLIMATOLOGY OF THE LATE PALEOZOIC 247 



were, as a rule, depositing red formations with gypsum, and locally, as in northern 

 Germany, alternations of salt with anhydrite or polyhalite in thicknesses up to 

 3>395 feet. In certain of these zones there were developed annual rings so 

 regular in sequence as to lead to the inference that they were the depositions of 

 warm summers and cold winters, enduring for at least 5,653 years (Gorgey, 1911)." 



With reference to the insect life, Schuchert says:^ 



"The very large insects of the Coal Measures tell the same climatic story, 

 for Handlirsch 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. * * *" 



[In Permian time] "the grand cosmopolitan swamp floras of the Upper 

 Carbonic, consisting in the main of spore-bearing plants, such as the horsetails 

 (equisetales), the running pines, and club-mosses (lycopodiales), and the ferns, 

 among which were also many broad-leaved evergreens (cordaites) and seed- 

 bearing ferns (cycadofilices), were very largely exterminated in the southern 

 hemisphere at the beginning of Permic time. In the northern hemisphere, how- 

 ever, the older flora maintained itself for a while longer, as best seen in North 

 America, but finally the full effects of the cooled and glacial climates were felt 

 everywhere. Then in later Permic time the old floras completely vanished, 

 except the hardier pecopterids, cycads, and conifers of the northern hemisphere, 

 and with these latter mingled the migrants from the hardy Gangamopteris flora 

 originating in the glacial climate of the southern hemisphere. Some of the trees 

 show distinct annual growth rings, and hence the presence of winters. It was 

 these woody floras that gave rise to the cosmopolitan floras of early Mesozoic 

 time. 



"With the vanishing of the cosmopolitan coal floras also went nearly all of the 

 Paleozoic insect world of large size and direct development, for the insects of late 

 Permic time were small and prophetic of modern forms. Then, too, they all 

 passed through a metamorphic stage indicating, according to Handlirsch, that 

 the insects of earlier Permic time had learned how to hibernate through the winters 

 in the newly originated larval conditions." 



The change in land vertebrate life has been repeatedly demonstrated 

 and the difficulties of interpretation caused by the discovery of generically 

 identical forms as low as Middle Conemaugh and as high as the Clear Fork 

 are removed by the position taken in this paper of a migration of the habitat 

 from east to west, favorable conditions appearing at later and later intervals 

 and at stratigraphically higher levels as the development of Permo-Carbon- 

 iferous conditions is traced to the west. 



The significance of "red beds" has been the subject of discussion for a 

 long time, and it now seems to be fairly well accepted that such deposits, 

 devoid of accompanying salt and gypsum beds, or with only a small per- 

 centage of such beds, is the result of a climate with moderate rainfall occur- 



1 Schuchert, Chas., Climates of Geologic Time, in Huntington, The Climatic Factors as 

 Illustrated in Arid America, Carnegie Inst. Wash. Pub. No. 192, p. 278. 



