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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with the relative position and thickness of each; some such a section, in
fact, as would be made by sinking a shaft about 4000 feet in depth, on
the eastern margin of the State, where the highest members of our series
form the surface rocks. To make this map and section intelligible, I
will briefly review the different formations represented on them.
THE SILURIAN SYSTEM.
Commencing at the bottom of the section, it will be seen that the first
step in our geological staircase is formed by what is called the Cincinnati
group, the Blue Limestone series of the former Geological Corps, and the
equivalent of the Trenton and Hudson River groups of New York. These
lie near the base of the series of unchanged fossiliferous rocks, found on
our continent, and belong to the Silurian system. Below all these lies
the great group of crystalline rocks-once stratified sedimentary beds,
but now upheaved and metamorphozed-which form the Eozoic system,
composed of two groups, the Laurentian and Huronian. These rocks are
exposed in a broad belt, extending from Labrador to Lake Superior, and
thence north to the Arctic Sea; a portion of.our continent not only composed of the oldest rocks of which we have any knowledge, but the oldest
portion of the earth's surface known to us; one that has never been submerged beneath the ocean since a period anterior to the formation of our
oldest palaeozoic strata.
We have evidence that at one time a broad continental area filled a
large part of the space now occupied by our North America, and was composed of the same rocks that now constitute the Canadian highlands. In
process of time this continent began to sink, and the sea gradually encroached upon its surface, ultimately covering all except the belt I have
described. From this sea, in its various advances and retrocessions, our
different geological formations have been deposited. These consist of
sandstones, shales, limestones, or some commingling of these different
rocks. The mode in which these strata have accumulated may be described
in a few words. All continental surfaces are constantly suffering erosion
by the influence of rain, rivers and shore waves, and the material comminuted by these agencies is carried into the ocean basin and deposited along
the shore, frequently in distinct belts. The shore itself is composed of
rocks undergoing processes of comminution, gravel or sand. In deeper
water accumulates the finer material, washed from the shore itself, or
contributed by rivers. This settles in a belt parallel with the first, and
when examined is found composed of fine sand Or clay. Outside of this
second belt, and beyond the point where the wash from the land reaches,
there is constantly accumulating a stratum derived from the decomposition
of the various structures belonging to the animate forms inhabiting the
ocean. Most of these organisms are provided with calcareous shells, and