Peat Beds of Anticosti Island. 71 



the summits of hi^h mountains," and says that " a depth of 150 

 to 300 feet has been assisjned to it where it is exposed in a sea 

 cliff at the head of Kotzebue sound." He further states : " On 

 the flood plains of the larger rivers and generally throughout 

 all of Alaska, peaty deposits are forming in the same manner 

 as on the tundra, modified, however, by the growth of arbor- 

 escent vegetation and by the intrusion of sand and clay in places 

 that are flooded during the high-water stage of tlie rivers." 

 Russell suggests that such may have been the origin of some 

 of our present coal deposits, which is further reinforced by the 

 statement that the flora of the tundra is essentially crypto- 

 gamic and that " two species of Equisetum which may be 

 considered as representing the Calamites of former titnes 

 flourish in rank luxuriance over greater areas of the Yukon."* 



Instances of enormous peat deposits in the polar halves of 

 the temperate zones could be multiplied to great extent, while 

 instances of such in the warmer regions are few or wanting, 

 Schitnper stating that peat does not form in the tropics except 

 on moiintains over 1200 meters high.f 



Nor are examples confined to the present ; for David notes 

 the occurx-ence in New South Wales " of a group of Coal 

 Measures, over 230 feet thick, and comprising from 20 to 40 

 feet in thickness of coal (the Grreta Coal Measures)" being 

 " sandwiched in between the erratic-bearing horizon of the 

 Lower Marine Series and the similar horizon of the Upper 

 Marine Series,":}; while Chamberlin and Salisbury state : 

 "The coal beds that lie between the glacial beds attained the 

 usual thickness."§ 



It may be well to ask if such facts as the above do not have 

 great bearing on the question of the climate . of past coal- 

 forming times. It would appear that a series of comparative 

 studies on peats of tropical and polar climates, with particular 

 attention paid to possible different physical characters of the 

 plants composing them, might give data of importance that 

 would serve as criteria for distinguishing coal of different 

 climates. 



A second conclusion that has been reached is that deposits 

 of coal of continental origin may have many of the characters 

 of marine deposits and that in interpretations of tlie origin of 

 a coal bed, the absence of a fire-clay substratum, the pres- 

 ence of marine fossils, and great uprooting of trees are not 

 necessarily conclusive evidence of marine origin nor even 

 determining evidence against a continental origin by growth 

 in situ. 



* Russell, I. C, Bull. Geol. Soc. Amer., p. 99, 1890. 

 t Plant Geography {Eng. Trans.), pp. 381-382, 1898. 

 i Quart. Jour. Geol. Soc, London, p. 289, 1896. 

 § Geology, 2d ed., vol. ii, p. 605, 1907. 



