10 



POLAR EEGIONS. 



Polar of ice, perhaps 140 feet long, (the part above water,) 

 Regions. an d 15 broad. The base, which was invisible, was 

 * Y-" 11 ' probably much more extensive. The table, or roof, 

 consisted of rough fractured ice, covered with snow ; 

 the columns were of solid grey ice, and the arches be- 

 tween, of six or eight feet elevation above the water, 

 and perhaps ten feet span. The columns were three in 

 number. The original form of this mass, it is presum- 

 ed, was that of a high irregular, but flattish hummock, 

 raised upon a large and ponderous base. It had been 

 exposed to a considerable sea, by which the roof had 

 been greatly undermined on all sides, and at length 

 perforated in two places, a circumstance which often oc- 

 curs. As detached pieces of ice frequently turn round, 

 as on a centre, by the action of the wind, waves, and 

 other pieces in passing them, the irregular blocks sup. 

 porting the roof of this piece of architecture, appeared 

 to have been rounded by uniform attrition, whilst re- 

 volving so as to form these blocks into three columns. 

 After this was accomplished it had got into smoother sea, 

 but had yet been subjected to the action of a slightly ruf- 

 fled surface, so as to hollow out the columns near the le- 

 vel of the sea ; but some part of the roof being too much 

 undermined had been broken off, by which the centre 

 of gravity was changed so as to raise the columns and 

 roof about six or eight inches. The slight waves now 

 operating in a different place would reduce the columns 

 below more than they were above, and consequently 

 leave a moulding ; a second loss of weight from the 

 roof, which is continually happening in such kinds of 

 ice, would elevate the roof a few inches more, and give 

 rise to a second moulding. In this way, or somewhat 

 in this way, there is no doubt but the piece of ice in 

 question had been sculptured into the remarkable form 

 that it bore. 



The construction of the table, a form that likewise 

 frequently occurs, admits of an easy explanation. In 

 this kind of figure, the stalk is often elegantly formed, 

 and perfectly circular. The detrition of the sea, to 

 which it is exposed^ washes away the ice above the 

 level of the water, and undermines the top. The oc- 

 casional revolution of the mass, meanwhile, exposes 

 every part progressively to the action of the waves, and 

 thus produces a stem of a cylindrical form. When these 

 tables become too heavy for the diminishing stem, the 

 top breaks off, and leaves the ruin of the former struc- 

 ture an uninteresting and perhaps shapeless mass. 



Drift ice is, in general, merely the ruins of larger 

 masses ; it is, therefore, necessary that we should give 

 some description of fields and fioes, the spurce from 

 whence drift ice is chiefly derived. Occasional masses, 

 indeed, are the fragments of icebergs, but by far the 

 greater proportion is the product of field ice. 



Ice fields are common in the Greenland Sea. They 

 occur there in immense numbers, and of vast magni- 

 tude. On inspection from a ship's mast-head, they 

 appear to be interminable sheets of ice. They are oft- 

 en met with of the diameter of 20 or 30 miles ; and 

 'when in a state of such close combination that no in- 

 terstice can be seen, they sometimes extend to a length 

 of fifty or even a hundred miles. Their edges, from 

 frequent contact with one another, are often rugged, 

 bluff, and huromocky. The margin is a zig-zag or wav- 

 ing line, full of indentations and projecting points. 

 The surface of some fields is, here and there, regular 

 and smooth, for an extent of thousands of acres ; but 

 most commonly it is diversified with numerous hum- 

 mocks, either insulated or forming ridges and chains. 



The hummocks often reach the height of 30, 40, or P<.iar 

 even 50 feet. The average thickness of heavy fields 1 

 may be stated at about 20 feet, though some are con- ^-Y"" 

 siderably thicker, and formed of the most solid ice. 

 The general appearance of a heavy field of ice is bold, 

 Striking, and picturesque, particularly early in summer 

 or spring, before the melting of the snows ; but after 

 the commencement of the rains and fogs of July, the 

 sharp elevated hummocks become rounded and redu- 

 ced, the snow wastes from the surface, and replaces 

 the elegant whiteness with patches of naked ice and 

 pools of water, and in many fields exhibits a disagree- 

 able dirty surface, arising from a deposition of mud or 

 earth, which had been concealed by the covering of 

 Thus the fields met with near the arctic circle 



snow. 



appear about the end of summer to be rapidly wasting ; 

 but those of high latitudes, not being subjected to such 

 a high temperature, are probably little reduced. In- 

 deed such of the water as remains on these fields, to- 

 gether with all the snow that escapes dissolution, adds, 

 by its conglaciation on the return of frost, to the thick- 

 ness of the field. The picturesque quality of ice-fieUb 

 arises from the numerous and diversified form of the 

 hummocks from the brilliant covering of snow, deli- 

 cately shaded with blue in every cavern and recess 

 together with the prodigious extent of their surfaces, 

 and the contrast they form with the darkness of the 

 adjoining waters. 



Ice-fields, notwithstanding their vast extent of sur- 

 face, and deep immersion in the sea, are liable to a va- 

 riety of motions dependant on currents, winds, and the 

 contact of other ice. Currents are sometimes so ex- 

 tremely superficial, that bodies floating at different 

 depths will be differently affected by their influence ; 

 thin ice will be carried by them with considerable 

 speed, while thick or heavy ice is not sensibly moved 

 by them. Most generally, however, the action of cur- 

 rents extends beyond the depth at which field-ice 

 floats, and consequently operates on all kinds of ice of 

 this and inferior thickness in a uniform manner. The 

 influence of the wind over ^ice, however, is extremely 

 unequal. The heaviest fields obey its impulse; and 

 all ice acquires a motion, which increases as the thick- 

 ness of the ice diminishes. Besides the motion in the 

 direction of the wind, large sheets of ice are subject to 

 a revolving motion, arising from the pressure of thin- 

 ner ice, or ice having a greater velocity on the sides. 

 And every kind of motion is modified by the dimensions 

 and form of the mass of ice, the largest pieces drifting 

 the slowest, and pieces of a circular form, or having 

 equal diameters, the most directly to leeward. A long 

 slip of ice seldom moves in the way of the wind, un- 

 less its axis happen to lie parallel to, or directly across 

 the course of the wind. But, like a ship, being in- 

 clined to move in the line of its longer axis, its true 

 course is always found between that line and the di. 

 rection of the wind. 



These various motions of the ice prevent it from drift- 

 ing quietly in a body. They give rise, therefore, to par- 

 tial separations and openings, and frequently bring the 

 largest masses into contact. When fields that have 

 different motions thus meet, they perhaps come in 

 contact with a velocity of more than a hundred feet 

 per minute, and produce a most tremendous shock. 

 The effect of impulsion, indeed, from a body calculated 

 not unfrequently to weigh more than ten thousand 

 millions of tons, is scarcely within the power of imagi- 

 nation to conceive. The weaker field is crushed with 

 a frightful noise ; sometimes the destruction is mutual ; 



