50 



NA TURE 



[iMarch io, 1910 



is due. Only when this is white has the proper colour 

 of the water a full chance of manifesting itself. From 

 the heights of Capri I noticed that the shallow water near 

 the shore showed decidedly green, an effect attributed to 

 the yellowness of the underlying sand. 



A GEOLOGIC FORECAST OF THE FUTURE 

 OPPORTUNITIES OF OUR RACE.' 



'T'HE established custom of occasions of. this kind leads 

 "*■ the association to expect that its retiring president will 

 address it upon some theme connected with the field of his 

 own work. I shall not altogether ignore this custom, but 

 I have chosen a theme that is at once pecuUarly humanistic 

 and distinctly prophetic. Geology has not usually been 

 regarded as in any special sense a humanistic science, much 

 Jess a prophetic one. But it is just because it has not been 

 so regarded, and because I have fondly dreamed that it 

 might become tributary in an eminent degree to humanistic 

 problems and to a prophetic insight, that I have chosen the 

 theme assigned for the evening. 



Ever since the race came to a virile state of intelligence. 

 It has tried to peer into the future that it might guide 

 itself by its foresight. Now and then it has prolonged its 

 vision beyond mere temporary concerns, and has en- 

 deavoured to prophesy the end of the race and the destruc- 

 tion of the earth. At all stages the depth of its vision into 

 the things before has been close akin to the length of its 

 vision backward and to the depth of its insight into the 

 things about it. The lamp of the past and the illumination 

 of the present have been its light for the future. This must 

 doubtless always be its true method, for only as the race 

 sees far into the past, sees widely and deeply into the 

 present, has it any firm basis for a confident prophecy of 

 the future. Even in its early days, the race did not fail to 

 note that — though this may not be so of the ultimate 

 entities — the existing forms come into existence, live their 

 day, and pass away ; why not, therefore, the race and the 

 earth on which it dwells? Even as the race grows into its 

 fuller maturity and the horizon of its vision is enlarged, 

 there will doubtless still remain the conviction that there 

 has been a beginning of the current order of things, and a 

 like conviction that there will be an end. The enlargement 

 of vision will only serve to bring into view an additional 

 multitude of organisms and organisations that have come 

 into form, endured for a time, and passed away. Any 

 future change in human forecasts is not likely to be one of 

 method, but one of measure. Some of the features that 

 have entered into former prophecies will no doubt dis- 

 appear, and perhaps new ones be added. The forecasts of 

 pre-scientific times often made the doom of the earth hinge 

 on some lapse in the conduct of man — made a physical 

 disaster serve as a moral punishment. With a better 

 knowledge of the moral law and of man's place in nature, 

 this anthropic view will no doubt give place to a more 

 consistent insight into the sequences of the moral and the 

 physical worlds. 



In the earlier days of the race the backward look was 

 short, and the putative origin of the race and of the earth 

 was placed but a few thousand years in the past ; in con- 

 sonance with this, the forward look placed the end not far 

 in the future. So, too, as the beginning was made chaotic, 

 the end was made cataclysmic. 



The dawn of the earth sciences was followed by a new 

 forecast, and as these sciences grew this underwent revisions 

 and recasts. It was learned that the history of the earth 

 stretches back not merely for thousands but for millions 

 and tens of millions of years ; that the on-goings of the 

 earth are actuated by energies too broad and deep and 

 strong to be swerved in their course or brought to an end 

 hy the acts of those who dwell upon it ; that the march of 

 sarth-history has a mighty tread not to be measured by the 

 merits or lapses of even our favoured race. 



The trend of proohetic thought in the last century invites 

 a closer review. The basis of forecast lay fundamentally 

 in the mode of origin assigned the earth and in the general 

 trend of its past history, especially the trend of those 



\ Address delivered at Boston, Mass., on December 27, T909, by the 

 retiring president of the American Association for the Advancement of 

 Science, Prof. T. C. Chamberlin. 



NO. 2106, VOL. 83] 



agencies that controlled the conditions of life on 'ts surface. 

 The solar system was thought to have had its origin in a 

 gaseous or quasi-gaseous nebula. The earth, as a member 

 of the solar system, partook of this origin, and was con- 

 ceived to have been, at an early stage, itself a fiery, gaseous 

 globe. It is not needful here to review the special hypo- 

 theses or pay honour to their great authors from Kant and 

 Laplace to Lockyer and Darwin, for the sole feature that 

 potentially shaped the history of the earth was the early 

 gaseo-molten state in which they essentially concurred. An 

 alternative was, indeed, offered in the suggestion that the 

 earth might have grown up by the accretion of small 

 bodies, but it was then held by students of dynamics that 

 such an origin was inconsistent with the symmetry of the 

 system and the rotations of the planets, and so an origin 

 in the gaseous or quasi-gaseous form was almost uni- 

 versally accepted, as by compulsion. Later, the gaseous 

 earth, by cooling and condensing, was thought to pass into 

 a molten sphere wrapped in a hot, vaporous atmosphere. 

 This atmosphere was vast because the conditions required 

 it to contain all the water of the globe and all the volatile 

 matters that have since entered into the waters and the 

 body of the earth. At a later stage a crust was logically 

 made to form over the molten sphere, and the waters to 

 condense upon it, swaddling the entire globe, perhaps, in 

 ri universal ocean. By further cooling, shrinkage, and 

 deformation, the waters were thought to be drawn into 

 basins, the land to appear, and the history of the strati- 

 graphic record to begin. It is important to note that the 

 main agency in this hypothetical history was loss of heat ; 

 and so, with consistent logic, loss of heat was made to lie 

 at the bottom of the great events of the earth's subsequent 

 history, and, in the forecast, to be the chief cause of its 

 doom. From a plethora of heat, of air, and of ocean, 

 putative loss followed loss in the past, and by prophecy 

 loss is to follow loss in the future until emaciation, drought, 

 and frigidity mark the final state and the end of all life. 



As the body of the earth cooled and shrank and permitted 

 penetratjon, the ocean was made to enter it, and, by union 

 with its substance, was thought to have been suffering 

 loss in the long past and to be doomed to further losses 

 yet to come. By a like union of the constituents of the 

 air with the body of the earth, as time went on, the great 

 smothering atmosphere of the primitive days was suppos .-d 

 to be brought down first to compatibility with marine life, 

 later to the lower land life, and still later to the higher 

 air-breathing forms. 



Projected logically into the future, still further depletion 

 of the vital constituents, even to the verge of exhaustion,^ 

 attended with pauperisation and finally with extinction of 

 life, entered into the forecast. With the gathering of the 

 oceans more and more into the basins, and their absorption 

 into the body of the earth, with the persistent consumption 

 of the atmosphere, and with the progressive cooling of the 

 whole, the moisture of the air was thought also to have 

 grown less and less. At first a deep, warm mantle of 

 vapour and cloud hypothetically clothed the whole earth, 

 and even half-way down the geologic ages was thought to 

 have enshrouded the globe and to have given warm, sultry 

 climates to all latitudes. But this mantle at length was 

 made to give place to rifted clouds and clearer skies, and 

 later on to mild aridities, followed at length by desert 

 stages, which are even now supposed to be creeping out 

 persistently on the once fertile lands. Thus we reach our 

 own times at a putative stage -when heat and air and 

 moisture are running low ; thus the predestined end is 

 foreshadowed in the not distant future. 



The round conception of the history shaped it as a pro- 

 gress from excess to emaciation, a sliding down the scale ; 

 it made the life-history but an episode intercurrent in the 

 great decline from the too hot and the too much to the too 

 cold and the too little. 



The logic in all this is plausible. Starting with the 

 hypothetical premises, the conclusions seem to follow. 

 Variations of detail might well be found in the com- 

 plexities of the case. Especially might sources of supply 

 be assigned to offset waste and loss in some degree, but, 

 granting the premises, the conclusion is not easily escaped. 

 In point of fact, the general conception dominated the 

 geologic thought of the last century. Not only this, but in 

 no small degree it gave direction to the interpretations, and 



