August 5, 1910] 



SCIENCE 



191 



eruptives of the Keewatin are surface volcanics 

 or ash rocks. The sedimentary rocks imply land 

 and sea, cool waters in which life existed, and in 

 general climates and conditions like the present. 

 As these are the oldest known rocks, there is no 

 geological evidence that the surface of the earth 

 was ever too hot to allow water and life to exist. 

 Geologists and astronomers should bear this in 

 mind in their theories. 



Discussed by W. G. Miller, H. F. Reid, W. M. 

 Davis and the author. 



With permission from the society, an overture 

 from the American Philosophical Society was then 

 read, asking for encouragement of a plan for 

 American exploration in the Antarctic regions. 



On motion, the communication was referred to 

 the council for consideration and report back to 

 the society. 



Then was presented: 

 Theory of Isostacy: W. M. Davis, Boston, Mass. 



Discussed by H. F. Reid. 

 The Mechanics of Faults: Habet Fieldixq Reid, 



Baltimore, Md. 



The forces which can be considered as active in 

 producing faults are : horizontal tensions and com- 

 pressions; vertical forces (upwards or down- 

 wards) and horizontal drags on the under surface 

 of the crust. It was shown that, in a uniform 

 crust, horizontal forces alone would produce nor- 

 mal or thrust faults having hades of 45°; that 

 the available vertical forces alone would produce 

 normal faults with a smaller hade, and that the 

 addition of a tension to a vertical force increases 

 the hade, whereas the addition of a pressure di- 

 minishes it. Drags will generate pressure and 

 tensions; they may cause faults with horizontal 

 displacements. The elevation of large regions is 

 due to vertical and not to tangential forces. 

 Ore the Relationship of 'Niagara River to the Gla- 

 cial Period: J. W. Spencer, Washington, D. C. 



In the borings made in the Whirlpool-St. Davids 

 channel, there have been discovered the remains 

 of a cool-climate forest and soil at a depth of 186 

 feet below the surface, with the proof of three or 

 four glacial advances since that time, nearly like 

 the Pleistocene history at Toronto. Before the 

 cool epoch, named " Forest Glen," at least two 

 glacial epochs have left their remains in the 

 buried channel, which is further filled a hundred 

 feet, or perhaps two hundred, of which some of 

 the deposits may represent a still older epoch; so 

 that the preglacial origin of the buried gorge, re- 

 quiring an enormous lapse of time (of perhaps 

 millions of years) is indicated. The age of the 



modern Niagara River is also seen to be younger 

 than the glacial deposits about the western end 

 of Lake Ontario, though not as recent as those of 

 the latter Wisconsin epoch in other localities. 



Discussed by Lawrence Martin, F. B. Taylor, 

 W. M. Davis and the author. 



Partial Drainage of Niagara Falls in February, 



1909: J. W. Spencee, Washington, D. 0. 



The publication of this paper is a record 

 through photographs taken by the writer of phe- 

 nomena which may occur again. The whole of the 

 1,000 feet of the American Falls, SCO feet of the 

 main cataract adjacent to Goat Island and 200 

 feet next to the Canadian shore (where already 

 there had been a curtailment of 415 feet, owing 

 to power diversion) were drained. The causes 

 were: the permanent lowering of the basin above 

 Goat Island by about 18 inches, since 1890; the 

 low water of Lake Erie at the time, and strong 

 northerly wind during very cold weather. 

 The Origin of Cliff Lake, Montana: G. R. IVUns- 



FIELD, Evanston, 111. (Introduced by U. S. 



Grant.) 



Cliff Lake lies in south central Montana about 

 five miles northwest of the continental divide, 

 where the latter makes the pronounced bend that 

 partly encloses the basin of Lake Henry in eastern 

 Idaho. The lake was brought to public notice in 

 1872 by Hayden, who described it as formed in a 

 volcanic fissure. At the present time popular 

 belief ascribes the lake to a similar origin. The 

 paper discussed the evidence for the hypothesis 

 of volcanic origin and presents alternative evi- 

 dence to show that the lake, though set deeply in 

 a lava plateau, really occupies a portion of a 

 river valley that was interrupted in early ma- 

 turity by the advent of a glacier which left a 

 series of morainic dams and thereby produced a 

 group of small lakes, of which Cliil Lake is per- 

 haps the most notable. 



Discussed by W. M. Davis and the author. 

 The Rock Streams of Veta Mountain, Colorado: 



H. B. Patton, Boulder, Colo. 



Veta Mountain is an isolated, ridge-like moun- 

 tain some ten miles east of the southern end of 

 the main Sangre de Christo Range. It stands 

 some two thousand feet above its base and has 

 extremely steep slopes. On the west side of the 

 mountain are to be found two remarkable rock 

 streams that afford excellent opportunities of 

 studying the nature and origin of these interest- 

 ing physiographic features. The streams were 

 described in detail and their origin discussed. 



