72 PROCEEDINGS OF THE WASHINGTON MEETING 



RELATIVE AGE OF THE DETROIT RIVER SERIES 

 BY CLINTON R. STAUFFER 



The Detroit River series is that part of the so-called Monroe formation 

 which lies above the Sylvania sandstone. In an article on the "Nomenclature 

 and subdivisions of the Upper Siluric strata of Michigan, Ohio, and Western 

 New York." by Lane, Prosser, Sherzer, and Grabau, 1 this series was subdivided 

 as follows : 



[ Lucas dolomite 

 Upper Monroe or | Amherstburg dolomite 

 Detroit River Series] Anderdon limestone 

 [ Flat Rock dolomite 



The series is overlain by the Onondaga (Columbus or Dundee) limestone or 

 the lowest generally recognized Devonian of the region. Doctor Prosser orig- 

 inally defined the Lucas limestone as the upper portion of the Monroe and 

 states that "it includes all the rocks between the top of the Sylvania sandstone 

 and the base of the formation which Doctor Lane in Michigan has named the 

 Dundee limestone." 2 It is thus evident that the Lucas has been much re- 

 stricted in the later paper. However, it seems probable that the Upper Monroe, 

 or Detroit River series, includes beds not very well known at the time the 

 definition of the Lucas, limestone was written. There is not only some doubt 

 as to the stratigraphic order of these subdivisions, but very conflicting opinions 

 regarding the real age of the whole series. It may be that part of the con- 

 fusion lies in the fact that the faunas of these subdivisions are not entirely 

 distinct, and that they have been mistaken for each other in the various out- 

 crops. Only a small portion of any of the faunas of the series is as yet known. 



The Detroit River series is rather widely distributed. over Michigan, Ontario. 

 Ohio, and doubtless Indiana as well. In Ohio the Anderdon outcrops in the 

 quarries at Castalia ; the Amherstburg probably occurs at Fremont, certainly 

 at West Liberty, and the Lucas outcrops at numerous places along the margin 

 of the Onondaga (Columbus), in northwestern Ohio. It is especially well 

 shown and quite fossiliferous at Silica and Centennial, in Lucas County. In 

 Ontario the most extensively distributed division of this series is probably the 

 Amherstburg, at least so far as at present known. In addition to those along 

 the Detroit River, outcrops of this dolomite may be found near Woodstock. 

 Saint Marys, Wingham, Formosa, and McRae Point. The Lucas dolomite is 

 less perfectly known, but appears, to be represented in the outcrops at Kin- 

 cardine and perhaps the upper part of the outcrop above Reachville. The 

 Anderdon is not certainly known in Ontario, outside of Fssex County, although 

 it is quite well developed in Monroe County. Michigan. Probably the best 

 development of the series is along the Detroit River, but it is by no means 

 confined to that region. The salt shaft at Oakwood, 3 near Detroit, cut one of 

 the best and most complete sections through it that is thus far known, except- 

 ing, of course, the numerous well records. But the most accessible sections 

 are those that have been exposed in the vicinity of Amherstburg. Ontario. 



iBull. Geol. Soc. Am., vol. 19, 1907, p,,556. 



2 .Tour. Geol.. vol. xi, 1903, pp. 540-541. 



3 Mich. Geol. and Biol. Survey, Pub. 12, Geol. ser. 9, 1911, fig. 21, opp. p. 278. 



