DRIFT ICE. 27 



drifting nortliwards with the current diiïer both in their form and origin. Some, 

 which break away from steep upland valleys, present a great diversity of outline 

 and appearance. According to the lines of fracture or the tilt of the glaciers 

 shooting them seawards, they rise above the surface in the form of domes, peaks, 

 or needles. Others again, which are visually of vast size, take the shape of rect- 

 angular blocks with almost level upper surface. These are not of glacier origin, 

 but have been detached from the icy barrier skirting the flat coastlands at varying 

 distances. They do not melt even in summer. During the fine seasons of 1841, 

 1842, and 1843, Ross found that only on eighteen days the temperature rose three 

 or four degrees above freezing point. Some were fringed with transparent stalac- 

 tites, which this explorer was unable to explain, as he had never observed the ice 

 melting. 



As far as can be judged from the few observations hitherto made, the frozen 

 masses, 160 to 180 feet high, are simply the land ice gradually impelled seawards 

 by the pressure of the more or less inclined masses covering the interior of the 

 continent. Owing to their specific gravity they project for distances of even 

 10 or 20 miles beyond the coastline, while still adhering to the rocky bed. In the 

 neighbourhood of the barrier Ross found a depth of 250 fathoms, which is precisely 

 the depth at which icebergs rising 180 or 200 feet above the surface must, so to 

 say, " lose their footing," and float away freely. The weight of the icebergs being 

 about nine-tenths of that of marine water, nine-tenths of their volume must neces- 

 sarily remain submerged ; but the mass being generally broader at the base than 

 the summit, the depth of the submerged walls must be estimated at seven or eight 

 times the height of the exposed cliffs. 



Once detached from the continental sheet of ice by some rectilinear form of 

 breakage, the huge flotsam sets out on its long journey towards the equatorial seas. 

 Some of the blocks present a regular wall 5 or 6 miles long with arched openings 

 at the base. They look almost like some street frontage gone adrift, at times 

 sparkling in the sun, but more frequently wrapped in vapour, like some misty 

 phantom of the brain. A nearer view reveals a frowning stronghold faced by 

 mighty bastions ; embattled ramparts or gloomy recesses where the angry waters 

 disappear amid the flanking towers ; overhanging cornices with snowy draperies 

 pendent from the summit. The icy cliffs, standing out at a distance with even surface 

 of uniform dull colour, are now resolved into an endless variety of tints and outlines. 

 Throughout the whole thickness of the walls follow the parallel parting lines of the 

 successive snowy layers crystallized by pressure and the weather, drawing continu- 

 ally closer with the superincumbent weight, here and there warj^ed to serpentine 

 curves or else fractured with sharp fissures. The prominent parts are of a dazzling 

 whiteness, others shaded in blue, each slope, each crystal aperture the loveliest azure, 

 and at night the floating mass is all aglow with an opal phosphorescence. It drifts 

 slowly with the current, incessantly lashed by the waves breaking against it, as 

 against some rocky shoal. The crews of passing vessels often hear the continuous 

 thunder of the waters rushing through its cavernous recesses and dashing against 

 the inner walls. Then the sustaining pillars at last give way, the arched vaults 



