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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which is almost wholly wanting in the Clinton rocks of this portion of
the State. In color these rocks have no uniformity, varying not only in
different localities, but often, in closely adjacent beds, passing from a
marble-like whiteness through various shades of gray, pink, yellow and
red. The weathered surfaces have very generally a yellowish, rusty appearance, due to the oxydation of the iron that the rocks contain. The
crystalline beds take a good polish, constituting a marble of attractive
appearance. The Harrisburgh and Ludlow " marbles" are examples of
this quality of the formation.
The rate'of growth of this rock would seem to have been exceedingly
slow, as no sediments have contributed to the growth of the strata, but
they are generally composed, in every particle, of the broken stems and
cups of crinoids or stone-lilies. Sometimes, however, there are found associated with these fragments, representatives of the other groups of animals
that were named in the Blue Limestone series. Two or more species of
chain-corals are quite characteristic fossils of the upper beds.
The Clinton group is known within the county by several local names,
in addition to that of " sandstone," already mentioned; such as "Firestone,"-" Fire-proof stone,"-" Rotten Limestone,"-" Bastard Limestone." Among the quarry men it is sometimes called " Pink-eye."
Between the Clinton group and the Niagara, which immediately overlies it, there is uniformly interposed a layer of very fine-grained marl,
from 2 to 6 inches in thickness, which is to be included with the former
group. This marl abounds in the free, perforated, disc-like joints of crinoidal stems of very large species, and certain shells occur here that have
not been found elsewhere in the series. As a general rule the Clinton
rock is not even-bedded, but, where raised in the quarries, comes out in
irregular masses.
III. NIAGARA.
The Niagara formation has no such uniformity of character as the
groups already described. It consists in all cases of even-bedded limestones and marls, it is true, but the limestones have very different degrees
of' purity, while in hardness, compactness, color, and the presence or absence of fossil contents, they have a very wide range. The celebrated
Dayton stone-" Dayton marble" it is sometimes styled-may be assumed
as the standard of excellence in this series; but different localities exhibit
every degree of gradation, from the admirable qualities of this stone in
comp actness, durability and color, to the worthless "yellow-back" of the
quarrymen, or to the unconsolidated clays that are frequently found as
its equivalent. In Montgomery county, the lower layers of the Niagara
rocks are always thelfirmest and most valuable, the 5 to 10 feet immediately overlying the Clinton, constituting in almost every case the sources
from which the Dayton stone is derived. The varying thickness of the