Page:Polar Exploration - Bruce - 1911.djvu/64

60 ice be taken out of any intermediate part it is found to be relatively fresh, certainly not nearly so salt as the sea itself.

I shall return later on to this interesting question of the saltness of sea ice, at present I wish to deal only with general naked-eye structure. It can be seen that this ice is much more plastic than fresh-water ice. Fresh-water ice is relatively brittle, even in thin layers. Fresh-water ice, of the thickness of about 2½ or 3 inches, will bear the weight of a man, but a child's foot would sink through sea ice of similar thickness, as if going through a layer of tough glue. You can push a stick through it, and a seal can push his nose and head through from below to get a breath.

Now, if there be a slightly undulating swell running under this new ice one sees the ice following the same motion, but to a less marked degree. But the thicker and more solid the ice, the more resistance is offered, until there comes a point where the sea-swell is killed. On the other hand, if the motion of the sea be more violent the more solid fields and floes are strained to breaking-point, and split up, first into small floes of a mile or two or at least several hundreds of feet in diameter, and these in their turn being repeatedly strained, twisted, and hurled in the wild confusion of the storm against each other, against bergs or