Part I. Report of progress in 1869, by J. S. Newberry, chief geologist. Part II. Report of progress in the second district, by E. B. Andrews, assist. geologist. Part III. Report on geology of Montgomery County, by Edward Orton, assist. geologist.

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yond our reach. By reference to the geological map, it will be seen that
all the north-western corner of the State is colored with a dark tint, to
correspond with that of the Black shale belt between the Lake and the
Ohio. This is so colored, because we have lately learned that the Huron
shale forms the surface rock in this region over an area of several counties. In all geological maps made previous to the one now published, the
Huron shale is represented as forming the Lake shore from near Sandusky to Conneaut, and it has generally been supposed to be the equivalent of the Hamilton group of New York. During the progress of the
explorations of the last summer, however, we discovered that east of
Avon Point, this black shale nowhere makes its appearance in the State,
but that the shore of the Lake on the Reserve, is composed of another
and more recent group of shales. We have also obtained, in various
localities, fossils which prove that this formation represents, in part at,
least, the Portage group of New York; and that it is all more recent.
than the Hamilton.
Much of the doubt which has hung around the age of the Huron shale,,
has been due to the fact that it has been confounded with the Cleveland
shale, which lies several hundred feet above it, and that the fossils.
(without which, as we have said, it is generally impossible to accurately
determine the age of any of the sedimentary rocks) had not been found..
Yet, with diligent search, we have now discovered not only fossils sufficient to identify this formation with the Portage of New York, but the.
acute eye of Mr. Hertzer has detected, in certain calcareous concretions.
which occur near the base, at Delaware, Monroeville, &c., fossils of great,
scientific interest. These concretions are often spherical, are sometimes.
twelve feet in diameter, and very frequently contain organic nuclei, around.
which they have formed. These nuclei are either portions of the trunks.
of large corniferous trees allied to our pines, replaced particle by particleby silica, so that their structure can be studied almost as well as that of
the recent wood, or large bones. With the exception of some trunks of'
tree ferns which we have found in the Corniferous limestone of Delaware
and Sandusky, these masses of silicified wood are the oldest remains of'
a land vegetation yet found, in the State. The Silurian rocks everywhere
abound with impressions of sea-weeds, but not until now had we foundi
proof that there were, in the Devonian age, continental surfaces covered!
with forests of trees similar in character to, and rivaling in magnitude,.
the pines of the present day.*
The bones contained in these concretions are those of gigantic fishes,,
* Prof. J. W. Dawson, of Montreal, has made known a very rich and interesting flora
-similar to that of the coal period-found in the upper Devonian rocks of New Bruns —
wick; and has described many other land plants, from New York and Canada, obtained
from strata, some of which are of Hamilton age.