STEVENSON— INTERRELATIONS OF THE FOSSIL FUELS. 29 



the rapidly thickening moss and consequent rising plane of frozen 

 ground cut off nutriment from the existing roots, necessitating the 

 formation of a newer set nearer the surface. He measured one tree, 

 which had 24 inches of vegetable matter above the lowest horizontal 

 roots. At 6 feet above the surface it had 373 annual rings, so that 

 the growth of the peaty mass had been at the rate of one foot in 

 about 200 years. One foot of the compact peat lower down repre- 

 sents a much longer period. 



TyrrelP- has studied peat deposits in a great part of Canada. He 

 notes that in northern Canada the peat, 10 to 12 feet thick, often 

 rests on a plate of clear ice. The water for this came from springs 

 below the permanently frozen ground and it favored the growth of 

 peat mosses in summer. The peat of Canada, except in the southern 

 portion, consists practically of undecomposed moss from top to 

 bottom, as the intense cold prevents change, the lower portions 

 being frozen. In the Klondike region, the moss layer is rarely 

 more than 5 or 6 feet thick, but there may be below it a variable 

 mass of " muck," a mixture of sand and vegetable matter, the latter 

 not from mosses. This muck he thinks originated in part as vege- 

 table mould which has slidden down into the narrow valleys. It may 

 contain about 30 per cent, of plant material. 



Cochrane,^^ who crossed Siberia long ago, was more interested 

 in the people, the roads and the weather than in geology, but he has 

 given some notes respecting localities in eastern Siberia, where his 

 progress was impeded. On the return journey from Nishney 

 Kolymsk, N.L. 69°, E.L. 160°, southwestwardly to Okotsk, N.L. 

 60°, E.L. 142°, he travelled over a region of mostly overflowed 

 meadows, alder country and " marshy swamps " ; the last part of the 

 distance, 7 days' journey, is a continuous swamp covered, at times, 

 with fallen trees. Between Okotsk and Yakutsk, N.L. 62°, the route 

 from the Okota River passes for long distances across wooded 

 swamps ; for 50 miles east from the Aldan River, the region is a 



^~ J. B. Tyrrell, " Crystophenes or Buried Sheets of Ice in the Tundra of 

 Northern America," Joitrn. of Geology, Vol. 12, 1904, pp. 232-236; also letter 

 of August 3, 1915. 



13 J. D. Cochrane, " Narrative of a Pedestrian Journey through Russia 

 and Siberian Tartary," Amer. ed., Phila., 1824, pp. 220, 225, 234, 238, 319, 

 325, 342. 



