384 E. HUNTINGTON — GLACIAL PERIOD IN NON-GLACIATED REGIONS 



of a considerable number of cycles of increasing severity or length, tend- 

 ing toward a maximum, after which there ensued the well known series 

 of cycles of decreasing severity. 



Comparison of the Pleistocene and Permian Strophes 



The Pleistocene is not the only strophic period recorded in geology. 

 The most widely known of the others is that which occurred at the end 

 of the Carboniferous or beginning of the Permian. This period, to quote 

 Chamberlin,* was marked by a "glaciation the deposits of which aggre- 

 gate a greater thickness than those of Pleistocene times, and whose oscil- 

 lations, marked by accumulations of coal, were even more remarkable 

 than those of the Pleistocene glaciation." In addition to glacial beds, 

 there appear to be, as has been said above, at least two other great types of 

 strophic deposits, namely, alternating vegetal and non-vegetal strata, and 

 alternating layers of red subaerial strata and of green or white lacustrine 

 strata. If deposits of all three t3'pes were produced during the Pleisto- 

 cene strophe, it is highly probable that they were also produced during 

 the greater Permo-Carboniferous strophe. Deposits of the first two 

 types, glacial and vegetal, are already well known from the Permian or 

 Carboniferous beds of India, Australia, and South Africa. It is probable 

 that further study will disclose one or the other in various parts of the 

 world. 



Inasmuch as the third type, alternating red and green strata, has hith- 

 erto not been recognized as indicative of strophic conditions, attention 

 has naturally not been called to it in connection with the Permian. 



Possible climatic Significance op the Red and White Moencopie 



Shales op Utah 



In the desert county north of the Colorado canyon, in northern Arizona 

 and southern Utah, the Aubrey limestone, a formation well established as 

 of Carboniferous age, is capped by about 1,000 feet of variegated shales 

 and sandstone, chiefly red, as shown in the accompanying sections (figures 

 15 and 16, J and plate 39, figure 2). These Moencopie strata contain no 

 fossils, so far as is known, except at the base in the transitional beds 

 overlying the Aubrey. They have been called Permian because of their 

 stratigraphic position. It has generally been assumed that they are of 

 marine origin, but there is no proof of this. In describing them in a 

 paper on the "Hurricane Fault,"! Professor J. W. Goldthwait and the 



* T. C. Chamberlin : An attempt to frame a working hypothesis of the cause of Glacial 

 periods on an atmospheric basis. Journal of Geology, vol. vil, 1899. 



t Bulletin of the Museum of Comparative Zoology at Harvard College, Geological 

 series, vol. vi, no. 5, 1904. 



t Note to figures 15 and 16. — The sections shown In these figures are not exact In details 

 beyond what is shown by the printed list of formations. At the time when the sections 

 were studied their importance was not realized. 



