ISOLATION AND ENDEMISM IN NORTHEASTERN AMERICA AND THEIR RELATION TO THE AGE‐AND‐AREA HYPOTHESIS

Abstract

From a purely academic standpoint, it seems perfectly obvious that, given a static world, the longer a plant or a group of plants has existed the more time it will have had to spread and consequently the more space it can have covered. No one can doubt this truism; and if this were all there were to Age and Area the proposition would need no discussion. But, unfortunately, Dr. Willis insists that Age and Area is the general rule in a world which has been far from static, and he has saddled upon his axiomatic proposition a great body of corollaries and from it has deduced a vast number of conclusions, many of which are diametrically opposed to the experiences of other botanists. In studying Willis' numerous interlocking papers I find myself constantly impressed by the ease with which the great facts of Cretaceous and Tertiary and modern geological history are brushed aside, and by the way in which edaphic factors are swept into the discard. In the time at my disposal only a limited number of Willis' deductions can be discussed, but I have aimed to select a few matters about which I can speak through personal familiarity with the situation. At the eastern margin of the heavily glaciated region of North America lies an area of much interrupted lands which to a great extent passed unscathed through the Pleistocene glaciation. This is the area immediately surrounding the Gulf of St. Lawrence: the Gaspe Peninsula of Quebec, the Magdalen Islands, Prince Edward Island, northern Cape Breton Island, and western Newfoundland. During the past two decades much of my field work has been devoted to some of these areas, and I wish particularly to draw your attention to two of the regions, the Gaspe Peninsula and the island of Newfoundland. Both have long mountain ranges which stand high above the area of general glaciation, the Shickshock Mountains of Gaspe rising 2,000 to 2,500 feet above the region of general denudation, and the Long Range, which forms the backbone of western Newfoundland, likewise showing signs of general glacial activity only on its lower slopes. The two regions are, then, nearly unique in the latitudes of extreme Pleistocene glaciation, in that they both have ancient floras which locally outlived the alacial period; but, like the other regions in the glaciated