The unusual glaciation of the east coast is evidently owing to the north polar current carrying the ice masses from the north polar basin 4 south-westward along the land, and giving it an entirely arctic climate down to Cape Farewell.
Of the Urals, but the question as to the glaciation of the Urals still remains open.
Glaciation was formerly much more extensive, old moraines being observed down to 12,000 ft.
Glaciation.-In the central and western parts of the Tian-shan there exist numerous indications of former glaciation on an extensive scale, e.g.
The reason for this exemption from glaciation is the converse of that for the southward convexity of the morainic loops; for while they mark the paths of greatest glacial advance along lowland troughs (lake basins), the driftless area is a district protected from ice invasion by reason of the obstruction which the highlands of northern Wisconsin and Michigan (part of the Superior oldland~ offered to glacial advance.