Speaking very generally indeed, in this region it is the sea-ice which forms over the Ross Sea area during the winter, and is blown northwards by the southerly blizzards. Thus it is that floes from a few inches to twenty feet thick go voyaging out to join the belt of ice which is known as the pack.
It is clear that winds and currents are, broadly speaking, the governing factors of the density of pack-ice. The tendency of the pack is northwards, where the ice melts into the warmer waters. But the bergs remain when all traces of the pack have disappeared, and, drifting northwards. And the last stages of these, when the bergs have degenerated into 'growlers,' are even worse, for then the sharpest eye can hardly distinguish them as they float nearly submerged though they have lost but little of their powers.
A berg shows only about one-eighth of its total mass above water, and a berg two hundred feet high will therefore reach approximately fourteen hundred feet below the surface of the sea. There are two main types of Antarctic berg. The first and most common is the tabular form. Bergs of this shape cruise about in thousands and thousands. A less common form is known as the pinnacled berg, and in almost every case this is a tabular berg which has been weathered or has capsized. The number of bergs which calve direct from a mountain glacier into the sea is probably not very great. Whence then do they come?
To the biologist the pack is of absorbing interest. If you want to see life, naked and unashamed, study the struggles of this ice-world, from the diatom in the ice-floe to the big killer whale; each stage essential to the life of the stage above, and living on the stage below:
THE PROTOPLASMIC CYCLE
Big floes have little floes all around about 'em,
And all the yellow diatom couldn't do without 'em.
Forty million shrimplets feed upon the latter,
And they make the penguin and the seals and whales
Much fatter.
Along comes the Orca and kills these down below,
While up above the Afterguardattack them on the floe:
And if a sailor tumbles in and stoves the mushy pack in,
He's crumpled up between the floes, and so they get
Their whack in.
Then there's no doubt he soon becomes a Patent Fertilizer,
Invigorating diatoms, although they're none the wiser,
So the protoplasm passes on its never-ceasing round,
Like a huge recurring decimal ... to which no
End is found.
Extracts from Apsley Cherry-Garrard, The Worst Journey in the World
