The Arctic islands —Jan Mayen, Nova Zembla, Spitzbergen, Franz-Joseph Land and many others — are heavily ice-laden. Their largest glaciers are broad sheets discharging magnificent bergs into the frozen sea.
But it is on Greenland and the South Polar lands that glacier ice reaches its grandest de velopment. Excepting a narrow interrupted strip around its shores, Greenland lies buried beneath a continuous mantle of ice thousands of feet in thickness, through which only the rock tops of its highest peaks, called "nuna protrude. From this ice-cap huge glaciers pour into the sea, discharging icebergs of enor mous dimensions, some of which sail into the Atlantic thousands of miles from home.
Still greater is the South Polar ice-cap, probably over two miles in thickness. The sea front of some of the glacier currents it pours forth are from 100 to over 400 miles wide, from which flat-topped island-like icebergs 5 to 10 miles long are discharged. Here the great ens mical winter of the Glacial Period still exists in severe, serene grandeur.
Greater Extension of Glaciers.— That a great part of the earth in both the northern and southern hemispheres, now warm and fruitful, was recently covered by flowing, grinding ice, is well known. Over the eastern half of. North America from the Arctic regions to lat. or lower, moraines and beds of moraine material variously modified, grooved, scored and pol ished surfaces, with other characteristic traces of glacial action, are displayed in wonderful abundance and uniformity.
Along the mountain ranges of the west side of the continent they extend still farther south. The broad Rocky Mountain chain and the plains along its flanks abound in glacial traces on a grand scale. On the Sierra Nevada pol ished and striated rock surfaces, the most evan escent of glacier inscriptions may still be found as far south as lat. 36° ; while a degree or two farther north, at an elevation of 7,000 to 8,000 feet above the sea, there are broad glacier pave ments in so perfect a state of preservation that they reflect the sunbeams like glass and attract the attention of every observer.
Over the greater part of Oregon, Washing ton, British Columbia and the Arctic and sub Arctic regions about Bering Sea and north western Alaska, the rocks in general are less resisting, and the weathering they have been subjected to is more destructive. Therefore the superficial records of glaciation are less clear in these northern regions than in California.
But in all glaciated regions there are other monuments of ice action which endure for tens of thousands of years after the simpler traces we have been considering have vanished. These are the sculpture and configuration of the land scape in general,— the canyons, valleys, fiords, mountains, ridges and roches moutonnees, the forms, trends and correlations of which are specifically glacial and almost imperishable.
These also, it is true, suffer incessant waste, being constantly written upon by other agents. But because they are so colossal in size and peculiar in form and arrangement they continue to stand out clear and telling through every after-inscription, showing how great the ancient glaciers must have been, and how great are the geographical and topographical changes they have produced. Where man is busiest, even in the parks and gardens of New York, glaciated rocks shine and call attention to the story of the Ice Period; and in orchards growing on moraine soil around the town of Victoria on the west side of the continent, fruitful boughs drop apples and peaches on the edges of glacier pavements, while the harbor rocks are still bright notwithstanding the centuries of wave action they have been subject to.
Only yesterday, so to speak, much of our continent was buried under a dreary expanse of ice, as Greenland is to-day. It has left its trace in lake and swamp, in polished outcrop and rounded hill, in countless islands and fring ing fiords. Under the influence, however, of a gradually warming climate, the glaciers have wasted away into insignificant remnants. See GLACIAL PERIOD; PLEISTOCENE EPOCH ; GEOLOGY.
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