here are not only ice-fields, ice-floes, &c., in the polar seas, but there are ice-mountains, or bergs.
It was long a matter of uncertainty as to where and how those immense mountains, that are met with occasionally at sea, were formed. We are now in a position to tell definitely where they originate, and how they are produced. They are not masses of frozen sea water. Their birth-place is in the valleys of the far north, and they are formed by the accumulation of the snows and ice of ages. This is a somewhat general way of stating the matter; but our subsequent explanations will, we trust, make our meaning abundantly clear.
Icebergs are found floating in great numbers in the arctic seas. They drift southward each spring with the general body of polar ice, and frequently travel pretty far south in the Atlantic before the
