84 REPORT OF THE 



at Jonesville and Hillsdale, and at many points in the townships 

 of Moscow and Scipio. In Jackson county the formation 

 extends up into Liberty and Hanover, and has been pierced 

 nearly through at the depth of 105 feet in the well of S. Jacobs, 

 Jr., in the township of Pulaski. The most characteristic out- 

 crops are found in Calhoun county; and from that at Marshall, 

 the group has received its provisional name. At this place the 

 stratification is as follows: 



4. Sandstone, rather thick-bedded, reddish, 10 ft. 



3. Sandstone, dark-reddish, rather hard, very fossiliferous, 5 ft. 



2. Sandstone, reddish- green, homogeneous, thick-bedded,. 10 ft. 



1. Sandstone, light, greenish-gray, thick-bedded. 



Several characteristic outcrops occur in the township of 

 Marengo, Calhoun county. At Battle Creek the lower beds of 

 the group are seen in places, highly calcareous and very hard, 

 but filled with characteristic fossils. The formation has not 

 yet been seen in place in Kalamazoo and Allegan counties, but 

 numerous fragments of a purple sandstone are strewn over the 

 surface, identical in general aspect with some layers of the 

 group at Pt. au Chapeau, on Lake Huron. In Ottawa county 

 the group presents well marked exposures at several points 

 on sec. 21, T. 5 N., 15 W. — township of Holland. I am also in- 

 formed by Henry D. Post, Esq., of Holland, that an outcrop occurs 

 inT. 5 N., 16 West., near the shore of Lake Michigan. At these 

 points it embraces, as usual, the characteristic fossils. One 

 mile east of Eastmanville, on the wagon road from Grand 

 Haven to Grand Rapids, a cut in the valley of Deer Creek ex- 

 poses the laminated arena-argil) aceous strata belonging to the 

 lower part of the group; and where the same road crosses 

 Sand Creek, about four miles east of Lamont, numerous frag- 

 ments and other indications of the neighborhood of an outcrop 

 may be seen. In some of the fragments, which are highly 

 ferruginous, I found the best preserved fossils that I have seen 

 in the State, including Nucula, Orthis, Ghonetes and Orthoceras. 



Further north than this, the group has not been traced; and 

 even to this p int, the boundaries are poorly defined, in conse- 



