610 



SCIENCE 



[N. S. Vol. XLHI. No. 1113 



support of tlie supposed mingling of Oriskany 

 and Onandaga faunas at this place. That 

 conception seems to have resulted from the 

 failure to discriminate the lithologically simi- 

 lar Springvale sandstone which is in reality a 

 local facies of the Onandaga. 



The Onandaga fauna is composed of three 

 important elements. Many forms lingered 

 over from the Oriskany of this general region. 

 Others seem to he related to the inhabitants of 

 the Lower Devonian embayment of southern 

 Illinois. The most distinctive element is that 

 including the corals; it bears such marked 

 relationship to contemporaneous European 

 faunas as to indicate a shallow-water connec- 

 tion with that continent. The line of migra- 

 tion was probably, as suggested by Weller some 

 years ago, via the Arctic regions and James 

 Bay. 



The Delaware limestone of Ontario is essen- 

 tially the western equivalent of the Marcellus 

 shale of New York. Its fauna is transitional 

 between those of the Onandaga and Hamilton. 



The Hamilton fauna is much the same in 

 Ontario as in New York. In the main it is a 

 derivation from the Onandaga fauna but it 

 also contains many immigrants from South 

 America. In one locality the Hamilton rocks 

 are largely limestone and there the resemblance 

 of its fauna to that of the Onandaga is very 

 close. 



The Upper Devonian strata are for the most 

 part heavily drift covered and known only 

 from well records. The worms and lingulas of 

 the black shale, correlated with the Huron of 

 Ohio, indicate its contemporaneity with the 

 Genesee of New York. Nothing is known of 

 the fauna from the green shales of the Port 

 Lambton beds. 



Quaternary Geology 

 In the region adjoining the International 

 Boundary between Eainy Lake and Lake of the 

 Woods, unconsolidated deposits of Quaternary 

 age overlie the pre-Cambrian crystalline rocks. 

 The study^ of the surficial sediments has re- 



8 ' ' The Eainy Eiver District, Ontario, Surflcial 

 Geology and: Soils," W. A. Johnston, Geological 

 Survey, Canada, Memoir 82, 1915. 



vealed the presence of a single small remnant 

 of leached and weathered till deposited by 

 probably pre-Wiseonsin ice advancing from 

 the Keewatin center. It is overlain by drift, 

 reddish where weathered, but ordinarily gray 

 in its lower portion, which was deposited over 

 the whole region by ice of the Wisconsin 

 stage moving southwestward from Labrador. 

 Shortly after the retreat of this ice the dis- 

 trict was invaded from the northwest by the 

 Keewatin ice sheet of the same stage, which 

 deposited calcareous tiU and boulder-clay and 

 formed a marginal glacial lake. The latter 

 was enlarged as the ice margin withdrew and 

 glacio-lacustrine clays conceal the till over 

 large areas. The clays show seasonal lamina- 

 tion and the reviewer infers from the author's 

 statements that this "Early Lake Agassiz" 

 existed for about 750 years after the with- 

 drawal of the ice before its waters were 

 drained. An interval, sufficiently long to per- 

 mit of extensive weathering and the establish- 

 ment of drainage systems, followed the dis- 

 appearance of this lake and then the region 

 was gradually transgressed by the waters of 

 Lake Agassiz. These advanced southward with 

 increasing depth of the lake as the northward- 

 flowing streams were ponded by a slight re- 

 advance of the Labrador ice sheet. The lacus- 

 trine sands, gravels, and clays are overlain by 

 Recent deposits of wind-borne sediment and 

 the peat and swamp muck which filled shallow 

 depressions in the lake floor after its waters 

 had drained away. 



A less complex series of Quaternary de- 

 posits form the surficial materials of the Is- 

 land of Montreal.' Boulder-clay covers the 

 pre-Cambrian and early Paleozoic rocks nearly 

 everywhere on the island and is in some places 

 overlain by the Leda clay and Saxicava sands. 

 Only one drift sheet, the Wisconsin, has been 

 identified. The clays and sands are deposits 

 in an arm of the sea which occupied the St. 

 Lawrence valley during the " Champlain sub- 

 stage " immediately following the retreat of 

 the Labrador ice sheet. Both formations con- 



9 ' ' The Pleistocene and Recent Deposits of the 

 Island of Montreal," J. Stansfield, Geological 

 Survey, Canada, Memoir 73, 1915. 



