Land Ice of Arctic and Sub-Arctic Regions 37 



upon the Pleistocene lacustrine silts. If a snowdrift deposit, some 

 evidences of unconformity are to be expected. For naturally snow- 

 drifts are likely to sometimes collect on land surfaces thus burving 

 the vegetation previously growing on the land and preserving some 

 trace of it underneath any future beds of ice the snow might form. 

 Some evidences of vegetation are to be expected under the ice-beds 

 where they formed on or near the former lake shores, but the remains 

 in such cases are entirely different from those that snowdrifts might 

 bury. There appears to be no reason for confusing such occur- 

 rences. At Eschscholtz Bay the remains of vegetation associated 

 with the silts and ice are composed of sticks and twigs of trees, 

 some of them gnawed by beavers. This is an occurrence to be 

 expected on the shores of lakes in estuaries and near the mouths 

 of small streams. As before stated, when the Pleistocene beds were 

 elevated, and the former lakes drained, the deposits were thrown 

 into gentle folds, and no doubt some irregularities of bottom already 

 existed, such as may be accounted for by irregularities in the deposits 

 due to cross-currents and wave building forming areas favorable 

 for the retention of shallow ponds and lakelets ; also ox-bow lakes 

 which are common today in these regions. The hollows of the 

 undulating surface formed shallow basins of varying areas, with 

 impervious clay bottoms. The new land surfaces thus laid bare were 

 diversified by a large number of shallow lakes and ponds spread over 

 the formerly extensive lake bottoms. Today the old dead ice-beds 

 appear to be consistently associated with impermeable clay basins in 

 elevated positions. 



The more severe climate that appears to have gradually accom- 

 panied the elevation of the land froze these shallow basins of water 

 into the ice-beds we see today. Just as the large lakes were not 

 all drained at the same time neither did the freezing of the ice-beds 

 happen contemporaneously but progressed gradually as it does 

 today. I. C. Russell"" describes the process. The surface of the 

 new land was carpeted by a layer of moss that surrounded the ponds 

 and lakes. The moss encroached on the lakes from all sides. " As 

 the moss covers the lakelets more and more completely during a 

 series of years, the ice formed by the freezing of the water in winter 

 is more and more thoroughly protected, and is finally completely 

 shielded from the heat of summer. A body of clear ice is thus 

 formed in the tundra, similar to the strata of ice exposed at certain 



'' Notes on the Surface Geology of Alaska. Bull. Geol. Soc. Am., Vol. I, 

 1890, pp. 99-162. 



