always occurs in nature. The shape of ice crystals depends on the 

 conditions under which freezing takes place. (Fig. 28.) 



ICE EDGE: (I.A.l.f.) — The boundary at any given time between pack 

 ice and the open sea. It may be a regular line with considerable tight- 

 ening of the floes along the edge, or may consist of a succession of 

 belts or patches, or may be frayed out into a number of points and 

 bights, with perhaps off-lying isolated fragments. The position of the 

 ice edge depends on wind and tide and varies considerably from month 

 to month and from year to year. The average position for any given 

 month, based on observations over a number of years, is described as the 

 monthly ice limit. 



ICEFALL: (II. B.) — An interruption in the surface of a glacier caused 

 by an abrupt change in the slope of its bed, resulting in disturbed ice 

 usually in the form of steep or precipitous ice cascades. Icefalls inter- 

 pose serious obstacles to travel over a glacier surface. 



ICE FAT: (I.A.3.a.)— Grease ice. 



ICE FIELD: (I.A.2.f.) — The largest of sea ice areas. An ice field is so 

 called because of its size only (more than 5 miles across). The effects 

 of pressure, erosion, or age have no part in the definition. See floe. 

 (Figs. 20, 42, 43, 65.) 



ICE FLOWERS: (V.B.)— Delicate tufts of frost or rime resembling 

 flowers that occasionally form in great abundance on surface ice around 

 salt crystals as nuclei (Fig. 26) . 

 ICE FOG: (V.B.) — Fog formed of small, elongated ice crystals, usually 



under conditions of clear, cold, windless weather. 

 ICE FOOT: 



(1) (I.B.I. a.) — A class of fast ice consisting of ice formed along and 

 attached to the shore. The base of the ice is at or below low water 

 mark. The action of tide, waves, and sea spray causes the development 

 of the ice foot during the freezing season. Differences in the causative 

 factors are reflected in the differences in the ice foot. Types of 

 ice foot formations are: Tidal platform ice foot, storm ice foot, 

 drift ice foot, stranded ice foot, false ice foot, and wash and 

 strain ice foot. See fast ice. (Figs. 53, 54.) 



(2) (II.A.) — The ice at the front of a glacier. 



ICE FRINGE: (I.A.l.f.) — A belt of sea ice extending a short distance 

 offshore. 



ICE GANG: ( IV. ) —Debacle. 



ICE GORGE: (IV.) — The damming of a river by ice fragments. The 

 ponded river water above the dam may cause serious floods. Cf. ice 

 jam, debacle. 



ICE GRUEL: (I.A.3.a.) — A type of slush formed by the irregular freez- 

 ing together of ice crystals. 



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