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SCIENCE 



[N. S. Vol. XXXVII. No. 947 



master the spiritual nature and the spirit- 

 ual development of the individual and of 

 the race. 



And, finally, our view of man as the 

 measure of all things is an exhortation to 

 an increase of sympathy and of sympa- 

 thetic cooperation among all the different 

 sciences. Of the particular sciences and 

 their subordinate branches and subdivi- 

 sions, there is an ever-increasing number. 

 But their aim is one aim; and in the pur- 

 suit of this aim they should be as brethren 

 dwelling together in a spirit of friendly 

 criticism and also of friendly unity. The 

 aim of all human science is the better to 

 understand man by himself, and the greater 

 nature which environs him ; and the better 

 to adjust himself to this greater nature, in 

 the pursuit of his economic, social, artistic 

 and religious ideals. 



I venture to close with the words which 

 Plato puts into the mouth of Socrates as 

 he closes his conversation with Thesetetus: 



But if, Theaetetus, you liave or wish to have any 

 more embryo thoughts, they will be all the better 

 for the present investigation; and if you have 

 none, you will be soberer and humbler and gentler 

 to other men, not fancying that you know what 

 you do not know. These are the limits of my art; 

 I can no further go; nor do I know aught of the 

 things which great and famous men know or have 

 known in this or former ages. The office of a 

 midwife I, like my mother, have received from 

 God; she delivered women, and I deliver men; 

 but they must be young and noble and fair. 



George Trumbull Ladd 



PLEISTOCENE GEOLOGY OF NEW YOBK 

 STATE. II 



LAKES 



Glacial Lakes: Occurrence. — The term 

 "glacial" is used by the writer to include 

 only lakes which existed by virtue of a 

 glacier ice barrier. The lakes and lakelets 

 now existing and called "glacial" by some 

 authors should be discriminated mostly as 

 morainal or drift-barrier lakes. 



The conditions necessary for a glacial 

 lake are a valley or depression sloping 

 toward and blocked by the ice front. 

 These conditions were fulfilled in New 

 Tork on so large a scale, in area and time, 

 that the state, it is confidently believed, 

 held the largest number and the most re- 

 markable succession, with varied outflow, of 

 glacial lakes of any district in the world. 

 The reason for this superiority is found in 

 the peculiar topography of the western part 

 of the state. In the great Ontario-Erie 

 basin we have a broad depression with its 

 lowest passes on the east and west, and 

 with a deeply trenched southern slope 

 where lie the parallel valleys of the Finger 

 lakes. 



The only glacial lakes of which clear evi- 

 dence is preserved are those which lay 

 against the receding front of the latest ice 

 sheet. But it should be clearly understood 

 that every ice sheet which transgressed the 

 state blocked the waters both during its ad- 

 vance and its recession. 



We do not know what portions of the 

 Valley-Heads moraine, which now consti- 

 tutes the divide and forms the south limits 

 of the basin, were left there by Prewiscon- 

 sin ice sheets, but we may be quite sure that 

 the lakes during the advance of even the 

 last glacier were somewhat different in di- 

 mensions and relations from those of the 

 ice recession, which are the subject of our 

 field study. We may also be sure that the 

 earliest ice invasion found the series of 

 parallel valleys with fairly mature and 

 graded forms, and open clear through to 

 their heads, and the larger ones heading in 

 Pennsylvania. Those earliest ice-im- 

 pounded lakes must have been longer and 

 deeper in the valleys than the lakes of later 

 episodes, when the valleys had become more 

 or less occupied by glacial and lake de- 

 posits. The lacustrine conditions of the 

 episodes antedating the Laurentian ice re- 



