56 Smitkesonian Exploration in Alaska in 1904 



only such parts of the ice around the margins are preserved through 

 each year as become protected by the mantle of moss whose growth 

 gradually encroaches over the water from the shore margins each 

 season. Where the lakes on the tundra have grown comparatively 

 small and shallow, we almost invariably find on and near their 

 banks a layer of semi-buoyant turf or peat under w^hich in many 

 places ice persists the year round. In this way conditions are pre- 

 sented that permit of the water acquiring a considerable gas con- 

 tent and also considerable dirt from decomposing vegetable matter, 

 for quantities of vegetable organisms (diatoms) accumulate on 

 the bottoms of even these Arctic ponds and lakelets there to decom- 

 pose and evolve gases that may form bubble cavities in ice. By 

 partial thawing and freezing such ice may also undergo rearrange- 

 ments of its crystallographic structure as do salt and borax occur- 

 ring in beds. 



Before classifying ice as of snow or water origin upon the per- 

 centage of air it contains there is to be considered the phenomenon 

 called anchor, frazil, or specular ice, forming when temperatures 

 are very low. For instance, when the wind blows cold over a lake 

 surface, the temperature of the upper two, three or more feet is 

 reduced considerably below the freezing point and is colder than 

 a surface sheet of still ivater when ice begins to form. In the 

 former case the water is full of ice needles to a considerable depth 

 and forms a granular ice very different from that in the latter case, 

 when the needles congregate in a horizontal plane at the surface. 



Features of the Beresowka Locality 



" There are two very characteristic points about the Beresowka, 

 one of the large affluents of the Kolyma, (i) its large valley and 

 (2) a very winding course. This is particularly true of the part 

 where the mammoth has been found ; of this part Herz sketched a 

 plan on the scale of i : 84,000. 



" The remains of the mammoth lay on the left bank of the 

 Beresowka which is being more and more washed away by the 

 river. The Beresowka makes here a great winding by w^hich a low^ 

 alluvial peninsula (an island when the water is high) is formed, 

 covered with wallows and other shrubs. On the left of the Bere- 

 sowka there is a steep bank 55 meters high above the water, then 

 there is a terrace half a kilometer (about ^ mile) wide extending 

 for several kilometers (about 3 miles) along the river. The ter- 

 race is limited by a mountain range 120 meters high, which is sepa- 

 rated from a second range 180 meters high by a small depression 



