is a clear vision, an unselfish attitude, a willingness to coöperate for the general good. It would be my suggestion that a conference of representatives of colleges and universities be called for the purpose of formulating plans whereby the proposals here submitted may be put into effect. A general conference might first be held followed by special conferences in different geographical centers. It is needless to say that some of the changes will have to be made gradually. The adjustment of different faculties to the new situation might necessitate a period of two to three years in order that no unfairness to individuals might ensue. But all that is a matter of detail. I am chiefly concerned now with acquainting the public with the situation as I see it and with proposing perfectly practicable measures for its cure if we will but use them.

It is important to note that this discussion of the subject puts another face on the matter of financial support for our institutions of higher learning; that the cry for help which has gone up from those institutions, while in a way justified, is distinctly misleading in another way since it does not tell the public the whole truth, which is that the power to effect the cure for the present distressing condition is to be found largely within the institutions themselves. Merely another viewpoint, greater honesty, and more regard for the common weal are requisite for the purpose. A wonderful opportunity presents itself now for the universities to help themselves and to raise the plane of our higher education much higher than it now is. Will they avail themselves thereof?

CLIMATE IN GEOLOGICAL TIME

ANDREW C. LAWSON

The uncertainty of the weather makes it a matter of perpetual interest. No two days are exactly alike. Anticipation of what the day is to bring forth-sunshine or cloud, fog or rain, warmth or chill, is a universal morning stimulus. The seasons bring in rotation their contrasted pleasures, yet no winter is the exact counterpart of another, no summer is the same as the last. The years thus have each their own characteristics, which are the subject of comment at the time, but which soon fade in our memories, save for the great flood, the great drought, or the heavy snowfall, that becomes a mark in the calendar whereby we reckon the passing years. In any region this versatility of the weather and of the seasons falls within certain limits which define what we call the climate. We may compare the climates of different regions by setting these limits one against the other and noting their differences, or we may more conveniently compare mean values for the range of temperature, humidity, precipitation. But, inasmuch as we have to deal with a number of more or less independent variables, the definition of climates for purposes of distinction is not a simple matter. It thus happens that while we all know that the climate of New England is different from that of California, and know that the difference is large, we have no simple formula for

expressing that difference, but only long and inexact descriptions. When we attempt to compare two climates that are feebly contrasted, such, for example, as those of southern California and Arizona, our descriptions fail of discrimination and we are content to place them both in the comprehensive category of the arid climates. If, then, in the present state of knowledge, the definition of climates for purposes of comparison is difficult and unsatisfactory when we have to deal with existing conditions, how much more difficult and uncertain must be the characterization of the climates of the remote past and their fluctuations, when we have to deal not with a knowledge of temperature, humidity, precipitation, etc., but only with fragmentary records of the effects of these on the rocks of the earth's crust. Thus, in attempting to characterize the climate of the Pleistocene glacial period we are by no means certain whether the vast accumulations of snow and ice which mantled half of the North American continent were due more to a general decrease of temperature or to a general increase of precipitation. We might have today a recurrence of glacial conditions in northern Canada if there should occur either (1) a notable decline in the mean annual temperature, or (2) a notable increase in precipitation without much change in temperature.

If then I attempt to outline briefly some indications of the fluctuations of the climate of certain large regions in geological time, it will be understood that I make no pretense to be specific as to the details of the changes, or certain as to their causes. The general facts are, however, of extreme interest as a chapter of geological history which is being greatly enlarged at the present time.

At the outset it may be pointed out that certain changes of climate follow as a necessary consequence of (1) the variations in altitude of land masses and (2) the variations of the relations of sea and land. The uplift

of the eastern part of the continent when the Appalachian Mountains were formed undoubtedly greatly modified the climate of probably half of the continent. Similarly when the late Cretaceous sea invaded the interior portion of the continent from the present Gulf of Mexico to the Arctic, a great climatic change must have accompanied the physiographic transformation; and an equally important climatic change must have attended the withdrawal of that sea from the continental interior at the close of Cretaceous time. The Appalachian uplift, as well as the invasion and withdrawal of the Cretaceous sea, are but instances of events which recurred many times in geological history; and the most elementary knowledge of this fact necessitates the recognition of climatic variations over vast regions. Such variations, due to the shifting of geographic control, do not, however, in themselves suggest any fundamental change in the climate of the globe as a whole. They are readily understood, in a general way, as a redistribution of conditions in the continental regions not involving any serious modification of the aggregate effect.

But the most impressive climatic changes which have occurred in geological time, changes concerning which we have the most positive evidence, are those which have taken place under geographical conditions that do not appear to have been very different from those which prevail at the present time. I refer of course to the oncoming and the passing of the glacial climate of the Pleistocene period. If the continent of North America had very much the configuration in Pleistocene time that it now has, the change of climate which caused the northern half of the continent to be buried in ice cannot be ascribed to geographical rearrangements of land and sea; and the same statement of course applies to the amelioration of climate which caused the ice to vanish. When we learn further that northern Europe passed through the same vicissitudes in the same period of

time, the suggestion comes home to us with great force that the cause was a general one-so general that it must have affected the climate of the globe as a whole. And this question of the variation of the general climate of our planet far transcends in interest those minor, perfectly comprehensible redistributions of climate which I have already mentioned as due to geographical changes arising from oscillations in the relations of land and sea.

Our notions of the climatic changes of the Pleistocene period are necessarily dependent on our knowledge of the events in the geological record. In recent years that knowledge has been greatly enlarged by the activity of many investigators, and the ideas that formerly prevailed regarding the climate of the period have been correspondingly modified. In the days when the glacial hypothesis was first generally accepted as the explanation of the peculiar physiography of northern latitudes in America and Europe, it was supposed that the ice must have taken the form of a great polar cap extending outward in all directions continuously from the north pole to middle latitudes. This was the simplest hypothesis that could be formulated in view of the evidence then available as to the glaciation of northern lands. It pictured to the mind a single event of vast proportions which could only be accounted for by a radical change in the climatic conditions of the whole globe. With the progress of exploration and geological observation in northern latitudes this hypothesis was soon greatly modified; and in tracing these modifications we may with advantage confine ourselves to the consideration of the North American continent. It was found that the coastal portion of Greenland and extensive portions of the Arctic slope, for example, northern Alaska, had never been glaciated. The surprising fact was also discovered that in certain portions of the Arctic slope, for example, the region of the lower Mackenzie River, the direction of movement of the ice had been