516 THE ICE AGE IN NORTH AMERICA. 



ancient glaciation encountered. The atmosphere had been 

 purified by the formation of Palaeozoic limestones of great 

 thickness, and by the storing up of the principal coal-deposits 

 of the world ; and these changes in the air had quite surely 

 produced greater diversities of climate than before existed, 

 especially in respect to the range of temperature in the seasons 

 and in the several zones. Alternating beds of coal, shales, and 

 sandstones, which form the coal-measures, indicate oscillations 

 of level and climatic conditions much like those of the Qua- 

 ternary period ; * and bowlder-bearing deposits, sometimes 

 closely resembling till and including striated stones, while the 

 underlying rock also occasionally bears glacial grooves and 

 striae, are found in the Carboniferous or more frequently the 

 Permian series in Britain, France, and Germany, f Natal, J 

 India,* and southeastern Australia. || In Natal the striated 

 glacier floor is in latitude 30° south, and in India only 20° 

 north of the equator. During all the earth's history previous 

 to the Ice age, which constitutes its latest completed chapter, 

 no other such distinct evidences of general or interrupted and 

 alternating glaciation have been found ; and just then, in close 

 relationship with extensive and repeated oscillations of the 

 land, and with widely distant glacial deposits and striation, 

 we find a most remarkable epoch of mountain-building, sur- 

 passing any other time between the close of the Archaean era 

 and the Quaternary. The Appalachian Mountain system of 

 the United States, with its grand plications and upheaval of 

 the whole Palaeozoic group of rocks, belongs to this epoch, 

 and the same line of disturbance extends by faulting and up- 

 lifts northeastward to Gaspe and Newfoundland. In Europe 



* Croll's " Climate and Time," chap. xxvi. 



f " Climate and Time," chap, xviii ; Wallace's " Island Life," chap. ix. 

 \ "Quarterly Journal of the Geological Society," vol. xxvi, 18*70, pp. 514- 

 517; vol. xxvii, 1871, pp. 57-60. 



# " Manual of the Geology of India," Part I, pp. xxxv-xxxviii, 102, 109-112, 

 229. 



| " Quarterly Journal of the Geological Society," vol. xliii, 1887, pp. 190- 

 196. " Die carbone Eiszeit," by Dr. W. Waagen, " Jahrbuch d. k. k. geol. Reich- 

 enstalt," Vienna, 1888, vol. xxxvii, Part II, pp. 143-192; reviewed in the 

 "American Geologist," vol. ii, pp. 336-340, November, 1888. 



