74 LOWER PENINSULA. 



mile, when they again recede from the shore, which further south 

 is a low sand beach. 



The sand rock of Point of Barques Lighthouse is coarse-grained, 

 partly conglomeratic, full of nodules and granular crystals of iron 

 pyrites. In undecomposcd condition, it is rich in calcareous cement, 

 and ver}' hard ; its color is partly dark bluish, or, in weathered con- 

 dition, ferruginous brown ; much weathered portions which have 

 lost nearly all their cement are softer and often whitish. The bed 

 is quite fossiliferous. The surface of the ledge is rugose by fucoid- 

 like ramifications spread over it, and seams of it are often densely 

 crowded with casts of a Rhynchonella ; of other Brachiopods, a 

 species of Orthis, a Productus, a Syringothyris, a Spirifer of a large 

 kind, Streptorhynchus, Rhynchospira, Spiriferina, Terebratula, are 

 generally plainly recognizable, but are too imperfect for specific de- 

 termination or identification with forms of other remote localities. 



In addition to the Brachiopods, several Lamellibranches of 

 the genera Cypricardella, Schizodus, Aviculopecten, and of Gastero- 

 pods a large Pleurotomaria (Huronensis Winchelli), were found, as 

 well as a species of Goniatites, and a large form of an annulated 

 Orthoceras. A Proetus, the head of a Cyathocrinus, and stems of 

 other Crinoids, together with traces of Bryozoa, complete the 

 list of fossils found there by me. 



The order of sequence of the strata composing the section from 

 Port Austin to Point of Barques Lighthouse, is differently repre- 

 sented in Prof. Winchell's report of 1861, in which the same locali- 

 ty is described. It will be remembered that I consider the rocks 

 of Flat Rock Point, Hat Point, and Point of Barques as identical, 

 and occupying the highest position in the series ; next below them 

 are thin-bedded ledges of sandstone with a fossiliferous seam con- 

 taining Centronella Julia and Rhynchonella camerifera. A band of 

 conglomerate rock follows, and then we come upon the grind- 

 stones, which in their fossils are identical with the sandstones of 

 Marshall ; to the latter, shales, with seams of sandstone, are sub- 

 jacent, and last and lowest in the section is the sand-rock ledge 

 of Point of Barques Lighthouse. 



Prof. Winchell commences his section with the calcareous sand- 

 rock ledges west of Flat Rock Point, which he correctly identifies 

 with the sandstones of Marshall, but places as the highest of the 

 exposed strata, and, under a preconceived theoretical opinion on 



