96 
THIRTEENTH REPORT. 
of the river. Much less would such cross section show the Detroit 
river bottom bed of dolomite to overlay Anderdon limestone — to which 
river bottom strata Grabau and Sherzer have given the name of Amlierst- 
burg Dolomite. Neither will it show Sylvania Sandrock at the base of 
Flat Rock dolomite over this area. Nor are the strata of the Detroit 
river series of Upper Monroe age, except in the upper reaches of the 
river; and except as the Upper Monroe strata round the head of the 
extreme northerly limit of the Cincinnati anticline and circle back to 
southward. On the contrary, and with the exception noted, the character- 
istics of these strata are those of the Lower Monroe. Compared with 
the Ballville section of the Ohio Greenfield dolomite this rock also is* 
“a light-colored dolomitic calcilutite.” Like the Lower Monroe beds of 
Maryland these beds also are f“nearly all calcilutites, mostly thin- 
bedded, well stratified.” As in the case of the Raisin River dolomite, at 
a given horizon *“hemispherical masses protrude . . . having a finely 
laminated, concentric structure and apparently concretionary in their 
structure;” and, “locally the beds contain patches of iron pyrite.” The 
upper beds are almost fossil-free, which will not be said to be a character- 
istic of the Upper Monroe strata. And, in addition, the sharp directly 
southward dip of the strata in all the central part at least of the area in 
question is in itself a statement of the fact that here is the rock 
against which the Upper Monroe banks, stratum upon stratum, with dip 
swinging from westward to northward in Monroe and Wayne counties. 
One further remark about the age of the Anderdon limestone beds. 
Professor Grabau has emphasized their Devonic affinities. I have shown 
that these beds do not sandwich between two dolomities; that they rest 
upon a dolomitic limestone transitional in character and Devonic in its 
chief characteristics; and that they are Devonic in chemical properties, 
analyzing in some instances 99.55 CaC0 3 . And, whereas f Grabau de- 
scribes a the Monroe beds and underlying formations (as) all involved 
in slight folding which tool c 'place in post-Monroe and pre-Dundee times” 
I have shown the Anderdon limestone beds occupying the synclinal 
space between two of these lateral folds. 
Altogether it would appear that the Anderdon Limestone beds have 
been wrongly classed as Siluric; in short that they are of Devonic age. 
Amherstburg. Ontario, March 28th, 1911. 
♦Stratigraphy. Structure and Local Distribution of the Monroe Formation; by Professors W. H. 
Sherzer and A. W. Grabau. 
t “Correlat’on of the Monroe Format on of M’chigan. Ohio and Canada with the Upper Siluric of 
Eastern North America and elsewhere,’’ Mich. Geolog. Survey, 1909, The Monrce Formation. 
