under the ice, through which meltwater flowed during the 

 "retreat" of the icecap when the ice itself was no longer moving. 

 Another theory supposes that they were formed on top of the ice 

 but also in stream beds, and were then gently let down to earth 

 as the ice rotted away below them. Since they look as though 

 they were man-made, they are rather startling when first seen. 



ince. This strip runs from the region of Akron, Ohio, south to 

 Nashville, Tennessee, and may be extended to include the Nash- 

 ville basin. It is an extremely fertile belt, second only to the 

 Central Lowlands in this respect, but it remains much more 

 heavily vegetated, with closed-canopy forest over large stretches. 



THE GREAT LAKES BASIN ' 



The theory that the enormous basin of the Great Lakes is ini- 

 tially due to a sagging of the crust of the earth is viewed with 

 disfavor by some. These critics note that before the first ice 

 advance the whole area was manifestly well above sea level 

 because it was amply drained by large river systems of which 

 there is still geological evidence, whereas now the bottoms of the 

 lakes themselves, but only of the lakes, are in some places as 

 much as three hundred feet below sea level. This school of 

 thought supposes that these huge troughs were bulldozed out by 

 the ice. There is possibly as much to be said for one theory as 

 the other, but it is observable that the area as a whole is now 

 rising, and it appears to have been doing so steadily since the 

 icecap went away. The Hudson Bay basin has also been rising, 

 but there is a contrary proposal about its past history too: 

 namely, that the central dome of the icecap never did lie over 

 it but was, rather, divided into two, one centered on the Keewatin 

 and the other on the Quebec— Labrador peninsula; and that the 

 ice flowed into it — rather than out of it — from both sides, 

 meeting along a line down its center that then extended south 

 from James Bay by way of Niagara to and down the Hudson 

 River Gorge. 



It does indeed seem that two opposed ice sheets from the 

 northwest and the northeast met in the Great Lakes area, spewed 

 on side by side for some distance, and then separated, one 

 turning east to reach the Atlantic at Long Island, the other con- 

 tinuing south to form the great sheet that reached the region of 

 St. Louis. As this combined icecap retreated for the last time, an 

 ever changing series of huge lakes was formed along its front. 

 At first these drained south to the Gulf, but, as the land was 

 progressively released northward, outlets broke through to the 

 Atlantic via the Hudson and St. Lawrence valleys, and finally to 

 the north into Hudson Bay. As the land sprang back from its 

 overload, the lakes contracted until they took up their present 

 conformations. Finally, Lake Ontario broke through to the 

 St. Lawrence and its waters drained off suddenly to a depth of 

 nearly two hundred feet, causing the waters of Lake Erie to start 

 spilling over a great bluff, thus forming Niagara Falls. 



At the present time the lip of those falls is cutting back at an 

 average rate of about four feet a year; but the rate of cutting in 

 the past has changed, as may be seen from the variations in the 

 size of the gorge below. The time since this cutting began has 

 been estimated at a minimum of ten thousand years; however, 

 other evidence appears to indicate that the icecap still covered 

 the falls at that time, which brings the date of the end of the 

 last "ice age" very much nearer to the dawn of our history than 

 had previously been supposed. 



The Western Piedmont and the Interior Highlands were not 

 apparently glaciated, but there is scattered evidence of the 

 existence of morainic and other glacial-type deposits in both 

 areas, which suggest that considerable snowfields with glaciers 

 might have formed on their higher levels for short periods. The 

 Western Piedmont, which forms a wedge lying between the Ohio 

 and the Cumberland rivers, is composed of the foothills of the 

 Appalachians, the eastern flank of which merges with this prov- 



ANIMAL IMMIGRANTS 



All of this gives us a new view of this province as it is today 

 and goes far toward explaining the appearance of the land, its 

 vegetation, and its animal life. It is a new province, repopulated 

 from the northwest, the south, and to some extent from the 

 uplands of Appalachia to the east, where a temperate flora and 

 fauna seems to have been able to survive all four ice advances. 

 This was once a land of continuous forests, and it must have 

 been exquisitely beautiful. There lived forest bison, elk, great 

 droves of white-tailed deer, black bear, puma, bobcat, and all 

 the lesser folk like raccoons, skunks and, above all, beaver. We 

 must say once more, though we will repeat it again and again, 

 that the latter animals have probably had more to do with the 

 landscaping of our continent than any other animal. They were 

 the first animals to move in the moment that the land was freed; 

 they will work right up to an ice front; and, above all, they do 

 something, and that of a nature that produces profound physical 

 results. Much nonsense has been written from time to time about 

 the beaver, but they literally move mountains, dam whole water 

 systems, and, by stemming the natural processes of erosion, 

 build fertile land; thus, they alter the composition of vegetation 

 by changing the water table, and perform many other works on 

 a vast scale. However, they categorically do not do this "by 

 taking thought upon the matter." To the contrary, they appear 

 to do it all in a kind of bumbling and entirely unimaginative 

 manner — just digging and ditching all the time by some kind of 

 built-in compulsion, whether the results be satisfactory to them- 

 selves or not. Simply by the law of averages plus the fact that 

 failures are automatically eliminated, the results of all their 

 activity are, on the whole, in accord with what their species 

 most needs to get along. And it just so happens that these results 

 are also highly advantageous to man, particularly to agricultural 

 man. If the beaver does the right things, he obtains a better 

 living environment — ponded water, flooded land, good pastures, 

 hardwood trees with the right bark to eat, and so forth — and 

 all these things are just exactly what modern man also wants. 

 All over this province, as in large parts of Appalachia, you 

 will see either such useful activities being currently prosecuted 

 or the good results of the past industry of these remarkable 

 animals. 



Large parts of three of the subprovinces are still well forested. 

 This is the land of maples, oaks, and beeches, and it was once 

 that of the American Chestnut, now virtually eliminated as a 

 result of a disease that spread all over the country with ex- 

 traordinary rapidity between the years 1904 and 1914. There is 

 still some true wilderness in the Interior Highlands, and in 

 northern Wisconsin and Michigan. Its vegetation as a whole is 

 very much like that of Appalachia and the eastern seaboard; it 

 lies in the same world belt as most of Europe, and it is usually 

 regarded as rather ordinary but somehow "proper" by a high 

 proportion of visitors, both American and foreign. 



Overleaf: A flight of teal over a marsh dotted with muskrat 

 lodges. These lodges are like those of the beaver but are 

 made of rolls of grass and sedges. 



86 



