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.

114
clay sometimes comes down into the coal, filling cavities. The following
diagram exhibits two of these " clay veins." (See Fig. 21.)
(Clay lcs n
FIG. 21.'On the west branch of Sunday creek, in Monroe township, I saw two or
three places where the coal was entirely gone, and the vacant space filled
with a yellow shale. At one point it is cut squarely off where it is 10
or 11 feet thick. The sandy shales appear to have been shoved into the
depression, and not to have accumulated by slow sedimentary increments,
as there was little appearance of lamination. At another place, the coal
seam grows smaller, and ends in a ball of coal, as seen in the accompanying figure. (See fig. 22.)
~~Yell~~~~ww~~~hal~esl ASandrock
Coal
Clay'
FiG. 22.
It is evident, from the study of the strata immediately over the Nelsonyville seam, that there were most remarkable changes in the conditions of
deposition in very limited areas. While the strong currents brought in
and distributed sands in many places, at the same time there were near
by, comparatively still waters, where the finer sediments, which now constitute the yellow shales, were deposited. At times these shales were
brought above the surface, and the growth of vegetation afforded seams
of coal. At a subsequent time, there were current ways cut down through
these yellow shales and coals, removing even the great seam below. This
is seen on the farm of Benjamin Saunders, Monroe township, Perry county.
Fortunately these breaks in the continuity of the Nelsoville seam are rare
and of very limited extent. It should also be remembered as a part of
the history, that in some places the currents which brought in the sand
of the sandrock removed the top of the coal, sometimes the whole seam,
and left sandstone in the place of it. Hence, while below the seam the
strata are fine, quiet-water sediments, and (distributed with remarkable uniformity and evenness; above it we fi evidence of just the oppo