January IS, 1895.] 



SCIENCE. 



Gl 



ciated portions of hotli North America and 

 Europe, bj- the occurrence of comparatively 

 small areas of ice accumulation beyond the 

 extreme boundaries of the principal ice- 

 sheets. The latter condition, or ice invasion, 

 is indicated on the outer part of the drift- 

 bearing area eastward from Salamanca, N. 

 Y., tlu'ough Statcn and Long Islands, 

 Martha's \'inej'ard and Xantucket, where 

 the soft strata beneath the ice were dis- 

 located and folded. 



1.5. Glimatic Conditions Shown by North 

 American Inlerf/ldcial Deposits. Wak- 

 EEX Tpham, Somerville, Mass. 

 During the times both of general accu- 

 mulation and growth of the ice-sheets and 

 of their final recession, fluctuations of their 

 borders were recorded in various districts 

 by forest ti-ees, peat, and molluscan shells, 

 enclosed in beds underlain and overlain bj' 

 till. Such fluctuations, while the ice accu- 

 mulation was in progress, enclosed chiefly 

 arctic or boreal species ; but when the ice 

 was being melted away, in the Champlain 

 epoch, the remains of the flora and fauna 

 thus occurring in interglacial beds, as at 

 Toronto and Scarboro', Ont., may belong 

 wholly to temperate species, such as now 

 exist in the same district. The cold climate 

 of the Ice age appears thus to have been 

 followed by a temperate Champlain climate 

 dose upon the waning ice-border. 

 16. Glacial Lakes in Western Neiv York 

 and Lake Nezvf)err>/,the Succe.ssor of Lake 

 Warren. By H. L. Fairchild, Roches- 

 ter, X. Y. 



The paper presented evidence that the 

 finger lakes of central Xew York were all 

 pre-glacial in character and that during the 

 presence of the ice-sheet at their outlets 

 they were backed up and discharged south- 

 ward, as is abundantly showTi by deltas at 

 various heights on both sides of the present 

 divide. Professor Tairchild cited eighteen 

 glacial lakes from Attica on the west to the 

 Onondaga river valley on the east. These 



he has named from important towns now 

 on the sites, as Lake Ithaca for the glacial 

 form of Cayuga lake, which was ;55 miles 

 long, ri-lO miles broad and 1 100 feet deep. 

 It has been long known that when the ice 

 cover(>d western Xew York the great lakes 

 discharged at Chicago to the Mississippi 

 and the great lake formed by them is called 

 Lake Warren, and has left a good beach. 

 At a much later stage, when the !Mohawk 

 was uncovered, the waters ran to the Hud- 

 son, and the great lake on the site of On- 

 tario has been called Lake Iroquois. The 

 intermediate stage between these two, when 

 the discharge of the water covering western 

 Xew York was through the low jtass at the 

 south end of Seneca lake thi-ough Horse- 

 heads near Elmira, Professor Fairchild has 

 called Lake Xewl)erry. The elevations of 

 this and the Chicago pass are such that 

 when allowance is made for the depressed 

 condition of the area at that time, the exist- 

 ence of the lake can be demonstrated. 



The paper was discussed by Messrs. Mc- 

 Gee and Gilbert, who commended the 

 choice of the new name as felicitous and 

 timelj-. J. W. Spenser also spoke, but dif- 

 fered w'ith the author in some points. 



Meantime, in the upper laboratorj- (the 

 Williams room), the petrographic .section, 

 under the chairmanship of Professor B. K. 

 Emerson listened to 

 18. The Relation of Grain to Distance from 



Margin in Certain Rocks. Alfred C. 



Laxe, Houghton. Michigan. 



A description of the variation in texture 

 and grain of sonn' quartz diabase dikes of 

 Upper Michigan was given, and the same 

 compai-ed with eft'usive flows of similar 

 mineral composition. These descriptions 

 were based on series of thin sections of 

 kno\^n distance from the margin. Inter- 

 stitial micropegmatite is primary or pneu- 

 matolytic, and the feldspar crystallization 

 begins before that of the augite,' continuing 

 until later. The distinction between the 



