408 



SCIENCE 



[N. S. Vol. XXVII. No. ( 



limestones and associated fragmental rocks 

 of what lias been called the Grenville series 

 proper. The view that the Grenville and 

 Hastings constitute one series, the former 

 being a more highly altered phase of the 

 latter, is no longer tenable. 



The writers find the Keewatin series of 

 the Lake Superior region represented in 

 southeastern Ontario by ancient rocks of 

 like character. The Grenville limestones 

 have been deposited on the surface of the 

 Keewatin. The writers class the Gren- 

 ville limestone as regards age with the Kee- 

 watin iron formation of Lake Superior, 

 which it has not been found possible in 

 that region to separate from the green- 

 stones. The pre-Cambrian conglomerate 

 and associated sedimentary rocks overly- 

 ing, unconformably, the Grenville lime- 

 stone, are classed as Huronian. The con- 

 glomerate contains not only ordinary frag- 

 ments of the Grenville limestone, but 

 "eozoon"-like boulders as well, thus 

 showing that the limestone is much older 

 than the conglomerate. Moreover, the 

 "pebbles of cherty and ferruginous rocks 

 resembling those found in the iron ranges 

 of Lake Superior" in the conglomerate of 

 eastern Ontario are found by the writers 

 to have been derived from layers or bands 

 of this material in the Grenville limestone. 



The paper was read by Mr. Miller and 

 the discussion was participated in by A. P. 

 Coleman, H. P. Gushing, C. R. Van Hise, 

 A. C. Lane and W. G. Miller. 



The next paper was 



Relation of the Equus Beds of Kansas to 



Reversed Mississippi Drainage: W. G. 



Tight, Albuquerque, N. M. 



Discussed by A. P. Coleman, H. E. 

 Gregory, A. C. Lane and F. W. Cragin. 



The following two papers were read 

 without intermission by Dr. A. C. Lane : 



A New Siluric Fauna from Michigan: W. 

 H. Sherzer, Tpsilanti, Mich., and A. 



W. Grabau, New York City. (By per- 

 mission of the state geologist of Mich- 

 igan. ) 



In the vicinity of Detroit some 275 feet 

 of dolomites and limestones overlie the 

 Sylvania sandstone, and constitute the 

 Upper Monroe. This series has been 

 traced through parts of Wayne and Mon- 

 roe counties and into the adjoining regions 

 of Ohio and Canada. A threefold division 

 is possible in the Detroit region, but in 

 most of the other localities one or more of 

 the members disappear by overlap on the 

 Sylvania as a basal bed or by pre-Onon- 

 daga erosion. A pronounced hiatus exists 

 between these Upper Siluric beds and the 

 Mid-Devonic Dundee limestone, which rests 

 disconformably on various members of the 

 Upper Monroe, or even on the Sylvania. 

 Two distinct faunse are recognizable in the 

 Upper Monroe. In the lower two members 

 the fauna is coralline, the middle member 

 (Anderdon limestone) being in most locali- 

 ties a more or less continuous coral and 

 stromatopora reef. A considerable num- 

 ber of species has been obtained from this 

 limestone. The corals are nearly all closely 

 allied to Mid-Devonic types. The stro- 

 matoporoids are chiefly Siluric, though two 

 Devonic genera with one species each oc- 

 cur. The brachiopods are Siluric, but the 

 pelecypods are of Devonic genera and spe- 

 cies not heretofore known from the Siluric 

 of America. The gastropods and cephalo- 

 pods, on the other hand, are all of Siluric 

 types. This remarkable fauna of the An- 

 derdon bed is soon displaced in the over- 

 lying dolomites by a more strictly Siluric 

 fauna, though even here species of Devonic 

 affinities are not unknown. The fauna of 

 Gothland is similar in many respects to the 

 highest Siluric fauna, the species, while 

 not identical, being closely representative. 

 The bearings of these facts on the paleo- 

 graphic conditions of North America in 

 late Siluric time will be discussed. 



