294 



SCIENCE. 



[N.S. Vol. XVII. No. 425. 



Ames Knob, North Haven, Maine; A Sea- 

 side Note: Bailey Willis, "Washington, 

 D. C. 



Ames KJaob is a mass of andesitic volcanic 

 rock rising 160 feet above the sea, on the 

 neck of land between the Fox Island thor- 

 oughfare and South Harbor, North Haven 

 Island, in Penobscot Bay. Its petrographic 

 character and geologic relations have been 

 described by G. 0. Smith, in his essay on 

 the geology of the Fox Island, Maine. It 

 is bounded on the north by a low plain 

 cut on shales and limestones, of Niagara 

 age, and its northern slope is a cUfE re- 

 sulting from the relatively great hardness 

 of the igneous rock. The other slopes of 

 the knob are of practically uniform rock, 

 and variations in profile are attributable 

 to conditions of attack, rather than of re- 

 sistance. At an altitude of approximately 

 eighty feet above the sea, on the south- 

 eastern and southern sides facing the At- 

 lantic Ocean, is a well-marked bench from 

 which a steep facet rises to the summit of 

 the knob. This bench, which has an aver- 

 age width of about 200 yards, is attributed 

 to the action of waves cutting at sea level. 

 The rocks in place exposed upon this bench 

 and about its margin exhibit rounded glaci- 

 ated profiles, but no longer bear striae, so 

 far as observed. Hence it is inferred that 

 the date of submergence to this level pre- 

 ceded or was nearly coincident with the 

 latest episode of glaciation, and that later 

 influences have removed the minor evi- 

 dences of ice action. Upon this glaciated 

 bench there are now deposits of glacial 

 gravel having the characteristic forms of 

 spits and bars, which are accordingly at- 

 tributed to wave and shore currents. These 

 deposits indicate the presence of the sea 

 at this level after the retreat of the ice. 



The simplest explanation of the facts is 

 that Ames Knob was submerged beneath 

 the sea to a depth of eighty feet above the 



present sea level during and immediately 

 after the latest glacial episode. 



Geology of Becraft Mountain, N. Y.: 

 Amadeus W. Geabaxj, New York City. 

 Becraft Mountain in Columbia Co., N. T., 

 is an outlier of the Helderberg Mountains. 

 Its base is formed by the upturned and 

 eroded rocks of the 'Hudson' group — 

 chiefly the Norman's Kill shales. Uncon- 

 formably upon this rests the Manlius lime- 

 stone (upper part), followed in turn by 

 the members of the New York Devonian up 

 to and including the Onondaga limestone. 

 A detailed geological map has been pre- 

 pared by the author for the New York 

 State Survey, Department of Paleontology, 

 and was exhibited by permission of the 

 State Paleontologist. The structure of the 

 eastern and southern portion of the moun^ 

 tain, which is of the Appalachian type, 

 was discussed. The excessive folding and 

 faulting of this portion of the mountain 

 was illustrated by a map and sections. 



In the petrographic section, Professor 

 B. K. Emerson presiding, the time was 

 largely devoted to a description and dis- 

 cussion of the new system of classification 

 of the igneous rocks which has been pre- 

 pared and published in a recent number of 

 the Journal of Geology by Messrs. Cross, 

 Iddings, Pirsson and Washington. By 

 means of charts J. P. Iddings first de- 

 scribed briefly the general principles on 

 which the system is based and the equi- 

 valent terms under the old system. H. S. 

 Washington then discussed the chemical 

 aspects and the methods and reasoning by 

 which the authors were led to their results. 

 He showed the chemical and mineralogical 

 confusion which exists in the old scheme 

 and the improvements afforded by the new. 

 Before discussion was called for, J. P. Id- 

 dings presented the following: 



