Notice of the rocks lying between the carboniferous limestone of the Lower Peninsula of Michigan and the limestones of the Hamilton group: with descriptions of some cephalopods supposed to be new to science
1862; Yale University; Volume: s2-33; Issue: 99 Linguagem: Inglês
10.2475/ajs.s2-33.99.352
ISSN1945-452X
Autores Tópico(s)Cephalopods and Marine Biology
ResumoXXXV.-Notice of the RIJcks lyt.•ng between the Oarboniferous L'/.'mestone of the Lower Pemnsula of Michigan and the k'mestones of the Hamilton Group: with descriptions of some Oephalopods supposed to be new to ~ j by ALEXANDER WINOHELL, State Geologist of Michigan.THROUGHOUT the counties of Hillsdale and Calhoun, and the southern half of Jackson county, in the Lower Peninsula of Michigan, occur frequent outcrops of a fine, friable ferruginous sandstone whose stratigraphical position in this part of the state, is not more than forty or fifty feet below the Carboniferous limestone.The whole thickness of the series is less than 800 feet.The upper portion of this succession of sandstone strata is more grayish than the lower, more firmly cemented, and more homogeneous j and it has thus far proved remarkably destitute of organic remains.The lower portion of the series, which is separated from the upper by:fifteen feet or more of shale, is of a dingy-reddish or yellowish color, with a very conspicuous amount of ferru~nous matter, often disposed in bands conformable with the lammation of the rock, or producing a rude concretionary structure, and not unfrequently solid nodules and bands of ironstone.At Battle Creek in Calhoun county, these strata, when not weathered, are of a bluish color, and firmly cemented by an abundance of calcareous matter.At Hillsdale and Jonesville in Hillsdale county, these sandstcmes are thicker-bedded, more fine and homogeneous, and incline more to an olive color.The lowest strata here are bluish, shal;v and highly micaceous.The most instructive exposures of thIS part of the sandstone series occur at Hillsdale, Moscow and Jonesville in Hillsdale county, and at Marshall, Ceresco and Battle Creek in Calhoun county.At most of these localities, esI?ecially those in Calhoun county, the sandstone is well stocked WIth fossil remains belonging to the genera Goniatites, Nautilus, Orthoceras, Bellerophon, Nucula, Solen, Myal'l.'na,Ohonera, &e.These lower fossiliferous sandstones have been designated the "Marshall Grou~," and the uEper, unfossiliferous beds the "Napoleon Group,' though it WIll appear obvious there are no very conclusive reasons for separating the two groups.From tbis part of the state, the outcroI>S of these two groups are believed to trend northeast and northwest in curved berts toward Pt.aux Barques and the mouth of Grand river.Toward the northwest, the next actual exposure known is in the township of Holland, Ottawa county, and west of there to the vicinity of Lake Michigan; though the intervening space affords numerous loose fragments of the formation.The Napoleon.sandstone is seen again near Grandville in Kent county, and
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