ISLAND ICE: (II.A.l.b.) — An island completely covered with land ice. 

 Island ice is similar in all respects to continental ice except that the 

 areal extent of the underlying land mass and the ice associated with 

 island ice is decidedly smaller. The quantity of ice covering an island 

 may be so great that the shape of the island ice approaches that of a 

 dome, and a selvage of land ice floating in the water may circumscribe 

 the island. 



LAKE ICE: (III.) — Ice formed in lakes. Lake ice is usually, but not 

 always, fresh ice. 



Wind and wave action may prevent the complete freezing of large 

 lakes when the air temperature falls below 32°F. On small lakes or 

 in the sheltered portions of large lakes, ice forms when air temperatures 

 fall below 32°F. 



When ice has formed, a further decrease in temperature causes shrink- 

 age cracks in the ice or breaks the shore contact, and additional water 

 freezes in the cracks and around the shore. When the temperature rises 

 expansion causes buckling of the ice or crowds the ice up the shore 

 slopes. Such crowding exerts sufficient force to affect structures along 

 the shore and to push lake bed materials shoreward above the water 

 line, forming ridges or bars composed of materials from the shallower 

 part of the lake bed. Such ice ramparts may be several feet in height 

 and may contain large boulders. Where conditions favor permanency 

 of ramparts once formed, successive shoves may build up a considerable 

 accumulation of displaced materials, forming an ice-push terrace. Ice 

 on lakes usually breaks up 5 or 6 weeks after the mean air temperature 

 has risen above 32°F. (Fig. 101.) 



LAND ICE: (II.) — Any ice formed on land masses, as an ice cap or 

 glacier. The existence of land ice depends upon air temperatures below 

 freezing and a supply of moisture for precipitation. Wright and Priestley 

 divide land ice into five major types: (1) Ice in the area of supply or 

 deposition, as continental ice, island ice, highland ice, cirque ice. 

 and snowdrift ice; (2) ice in the area of movement or transmission, as 

 wall-sided glaciers and valley glaciers; (3) ice in the area of wastage 

 or dissipation, as expanded ice foot, ice tongue afloat, piedmont 

 ice, confluent ice, and avalanche ice; (4) ice in the process of dis- 

 solution in the sea, as icebergs, bergy bits, and growlers; and (5) 

 ice in the area of balanced forces, as shelf ice. See ice. (Frontispiece, 

 Fig. 85.) 



LANDFASTICE: (IB.)— Fast ice. 



LAND FLOE: (I.A.2.) — An unusually thick fragment of fast ice which 

 has become detached and is now afloat. 



LAND SKY: (V.B.) — Dark streaks, patches, or a grayness on the under- 

 side of extensive cloud areas caused by the absence of reflected light 



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