ckinaw, Michigan:

"From the site of old Fort Mackinaw, at the very extremity of the
peninsula, south to the Manistee River, a direct distance of about one
hundred and forty miles, the immediate shores of the lake are almost
invariably considerably elevated, sometimes rising abruptly to a
height of from three to four hundred feet.

"The soil of the vicinity, in consequence of the large amount of
calcareous matter which enters into its composition, possesses a
fertility that a superficial observer would scarcely ascribe to it.

"The limestone chiefly consists of an irregular assemblage of angular
fragments united by a tufaceous cement. These fragments usually appear
at first sight to have a compact structure, but a more minute
examination shows them to contain _minute_ cells, sufficiently large
to admit water, which, by the action of frost, subjects the rock to
rapid disintegration. Portions of the rock may, nevertheless, be
selected partially free from this difficulty, and which are possessed
of sufficient compactness to render them of value as a coarse building
stone; horn-stone, striped jasper (imperfect); hog-toothed spar,
calcareous spar, and fluor spar, are imbedded in the rock, although
the latter is of rare occurrence.

"Lime rock again occurs at the Straits of Mackinaw, and in the
vicinity, it appears upon the Island of Mackinac, together with the
Bois Blanc, Round, and St. Martin's Islands, as also upon the northern
peninsula north from Mackinaw.

"Gypsum occurs on the St. Martin's group of islands, and also upon the
northern peninsula between Green Bay and Mackinac.

"MACKINAW LIMESTONE.--The rock is of a light color, and the fragments
of which it is composed frequently contain numberless minute cells.
These were undoubtedly once filled with spar, which has been washed
out of the exposed part of the rock by the action of water. The upper
part is unfit for building purposes, but the lower is more compact,
and has marks of regular stratification.

"COAL.--The coal is highly bituminous, a character in common with all
that has been seen in the State, and it may safely be said, that none
other may be looked for in the peninsula.

"From the facts now before me, I am led to hope that coal will be
found in the elevated hills of the northern part of the peninsula,
easterly from Little Traverse Bay, a circumstance which, should it
prove to be the case, will add much to the value of that portion of
the State."-