This in turn, by further compactins or pressure from jbove. 

 i-hanjjes to ice by partial melting and immediate revelation, or 

 refreozing. This new ice is white and usually opaque, due to its 

 myriad included crystalline faces and many minute air pockets 

 Later still, as the snows pile up above, this ice goes through 

 another change and is converted into pure crystalline ice The 

 air is absorbed, the crystal faces are obliterated, and the whole 

 becvmes one vast homogeneous and amorphous mass of clear 

 material, usually of a pale blue color and quite translucent. This 



When an icecap forms over a land surface and one cannot 

 form over water for various mechanical and chemical reasons — 

 It continues to grow as long as the mean average annual tem- 

 perature remains below a certain point and there Is sufficient 

 precipitation. The latter is by far the more important Even the 

 center of the Greenland icecap is by no means the coldest place 

 in the world, especially as compared to the Antarctic and to 

 some places in Siberia The all-time record low temperature was 

 recorded on Graham Land in the Antarctic ciunn.' i t h// ir.i i>,,i 



The parts of . 

 above, so thai 



about nine-tenths- beloiv the sea surface often melt faster than those 

 floats higher and displays wave-cut caves and platforms. 



substance is hard, breaks like a shard, and has some rather 

 strange properties. 



In fact, water is altogether an extraordinary substance. Both 

 as a gas (steam) and as a liquid and as a solid (i.e. ice. whidi is 

 really a rock) it comes in many forms. Then there are all man- 

 ner of intermediate conditions of a meteorological nature, such 

 as water vapor, fog. mist. snow. hail, and so forth, as well as 

 many most bizarre forms of ice; for instance, there is columnar 

 ice that looks like cigars packed together. In Siberia there are 

 large areas where, under the Arctic soil, lie as much as two thou- 

 sand feet of palaeocrystic or "fossil" ice; some of this is jet-blade, 

 but when a quantity of it is melted in a glass container, the 

 resultant water is as colorless as clear spring water. 



was -132 degrees F. The coldest known in the northern hemi- 

 sphere was -97 degrees F. in Siberia, which was actually south 

 of the Arctic Circle. 



Once an icecap is born it grows just like some vast amoeba, 

 and then it begins to move. As a rule it moves outward in all 

 directions because, however rigid and crystalline it may appear 

 to be. ice is still plastic and it becomes positively fluid under 

 extreme pressure. It then either flows outward, sliding over 

 itself in layers under the influence of gravity, or it is literally 



Overleaf: Icebergs are constantly calved by Greenland's gla- 

 ciers and then drift away: many end in the North Atlantic. 



