Q&- 
7 02- 
uvs [From the American Journal of Science and Arts, Vol. XXXIII, May, 1862.} 
iTe* a __ 
R7 3 
ON THE ROCKS LYING BETWEEN THE CARBONIFEROUS LIME- 
STONE OF THE LOWER PENINSULA OF MICHIGAN, <fcc. 
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 lime¬ 
stone. The whole thickness of the series is less than 300 feet. 
The upper portion of this succession of sandstone strata is more 
grayish than the lower, more firmly cemented, and more homo¬ 
geneous ; and it has thus far proved remarkably destitute of or¬ 
ganic remains. The lower portion of the series, which is sepa¬ 
rated from the upper by fifteen feet or more of shale, is of a 
dingy-reddish or yellowish color, with a very conspicuous amount 
of ferruginous matter, often disposed in bands conformable with 
the lamination of the rock, or producing a rude concretionary 
structure, and not unfrequently solid nodules and bands of iron¬ 
stone. 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 sandstones are thicker-bedded, more 
fine and homogeneous, and incline more to an olive color. The 
lowest strata here are bluish, shaly 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, especially those in Calhoun county, 
the sandstone is well stocked with fossil remains belonging to the 
genera Goniatites , Nautilus , Orthoceras , Bellerophon , Nucula , Solen, 
Myalina , Chonetes , &c. These lower fossiliferous sandstones have 
been designated the “ Marshall Group,” and the upper, unfossil- 
iferous beds the “Napoleon Group,” though it will appear ob¬ 
vious there are no very conclusive reasons for separating the 
two groups. 
From this part of the state, the outcrops of these two groups 
are believed to trend northeast and northwest in curved belts 
toward Pt. aux Barques and the mouth of Grand river. To¬ 
ward 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 
