284 



SCIENCE 



[N. S. Vol. LII. No. 1343 



the substitution of cheaper or more effective 

 methods. Unintelligent operation is truly 

 false economy, and legislation should not be 

 left to popular caprice, but be tempered and 

 directed by sound scientific knowledge. Espe- 

 cially in such a delicately balanced operation 

 as the scientific control of the natural waters 

 is it necessary to know the facts. Where a 

 small factor can determine the whole condi- 

 tion it is necessary to be familiar with all the 

 details. If a limiting factor can be removed 

 by a simple expedient it allows for expansion 

 all along the line until the next lower factor 

 replaces it. Perhaps this, in turn, may be 

 eliminated with slight treatment, and by suc- 

 cessive steps in biological technology can the 

 capacity of the stream be greatly increased 

 with the least expenditure of effort and money. 

 William Fieth Wells 

 Conservation Commission, 

 Albany, N. T. 



PLEISTOCENE CLAYS AS A 

 CHRONOMETER 



The Swedish expedition now in America, 

 led by Gerard DeGeer, has an ambitious pro- 

 gram of proposed discovery. Following are 

 quotations from his announcement: 



. . . the undersigned described how he had, 

 since 1878, worked out and utilized a method of 

 determining by actual counting of certain season- 

 ally distinct laminated clay layers, the chronology 

 of the past 12,000 years, or the period that wit- 

 nessed the evolution of man as well as of the 

 whole fauna and flora of those parts of northern 

 Europe and North America which during the Ice 

 Age were barren deserts covered by extensive ice 

 sheets, .... 



By the new method of investigation it has now 

 been shown to be possible to foUow, step by step, 

 how the large ice sheets receded and melted away, 

 this being registered from the melting season of 

 every year by the annual deposition of melting- 

 water sediment, and especially of seasonally lami- 

 nated clays. 



The annual lamina from warmed years being 

 thicker and from colder ones thinner, the chrono- 

 logical self -registering is at the same time a thermo- 

 graphical one. . . . 



It will thereby no doubt be possible by a kind of 

 primary triangulation to fix at a sufdcient num- 

 ber of points the very years when they passed by 

 the receding ice border. By interpolation between 

 the figures thus obtained and by help of the al- 

 ready mapped moraine-lines, now to be accurately 

 dated, the laws regulating the whole recession of 

 the great ice-sheet can certainly be established and 

 at the same time the rate by which the rideau was 

 pulled away from the stage of life and the amount 

 of time during which in every region of the 

 northern part of the New World the plants and 

 animals have had at their disposal for their immi- 

 gration and settlement; the tame required for the 

 development of the soil and the vegetable mould, 

 for the rivers and the lakes for their erosional 

 work, and for the evolution of our prehistoric 

 ancestor. 



Still, the most far reaching result of the whole 

 investigation might be that so rapid and at the 

 same time so widely distributed variations of the 

 temperature of the air scarcely can be attributed 

 to any other cause than variations in the amount 

 of heat reaching the earth from the sun. . . . 



If that program should be promptly carried 

 out the pleasure from scientific discovery by 

 future students will be reduced. Truly, a 

 yardstick of geologic time is greatly desired. 

 More desired than needed. We know that time 

 is long, but how long? The most cormnon 

 question to the geologist is " how long ago ? " 

 But if we knew the exact number of years since 

 the ice sheet disappeared from New York, 

 whether 31,676 or 109,322 years it might sat- 

 isfy some curiosity hut would make little dif- 

 ference in human life and race evolution. For 

 we know that geologic time is not to be meas- 

 ured by hirman standards, and when we deal 

 in millions of years the number of the millions 

 has little significance. The subject appeals to 

 the imagination, especially of the non-geo- 

 logic public, and if Mr. DeGeer can find out 

 even a part of his program he will make in- 

 teresting discovery and we applaud the effort. 

 However, lest the public should be too greatly 

 disappointed, it is well to realize some of the 

 difficulties in the study. 



The laminated glacial clays which are the 

 subject of measurement were deposited in deep 

 or quiet waters facing the receding front of 



