LYON—ROOKS OF KENTUCKY. 617 
formis is abundant at almost every outcrop of this mass 
which has been observed: other forms of Pentremites have been 
observed ; these have not been identified. When the place 
of the buff bed, at the top of this mass, is filled with marly 
clays, a variety of forms of Blastoidea are abundant and well 
preserved, 
k. Second Sandstone of the Millstone Grit series.—This mass 
of heavy bedded, coarse sandstone makes permanent cliffs, 
wherever it has been seen outcro ing in Western Kentucky. 
Locally, fossil tar exudes from the fissures of this mass, but so 
far as it has been determined, the source of the taris in Sand- 
stone No. 3 (A), and it must find its way downward through 
the fissures in the masses of i and k. The “tar springs” of 
Breckenridge County, Kentucky, are at the base of the mass 
of k, at which point it is eighty-four feet thick. It varies 
in thickness from 75 to 90 feet, and appears to have been con- 
tinuous around the coal beds in Western Kentucky. 
l. First Limestone of the Millstone Grit Series. —The mass of 
! varies both in thickness and the character of the materials 
Composing it. The remains of the fossils found in it are 
usually much worn. One outcrop exhibits the upper part of 
this mass as marly shale mixed with fragments of shells and 
corals, The general character of the mass of / is that of thick 
beds of lumpy, water-worn limestone. The characteristic 
fossil of this bed is Productus. 5 
m. The First Sandstone and the base of the Millstone Grit 
Series —The first sandstone in time rests on the upper part of 
the limestone variously designated as the “Barrens lime- 
stone,” “ Cavernous limestone,” “Carboniferous limestone, 
« Subcarboniferous limestone,” and in Europe as “Mountain 
limestone.” Some American authors prefer the latter desig- 
nation, The mass of m is generally Kin-beaded ; the strata 
rarely rise higher than two feet; the upper part of the erry 
Senerally consists of the thickest beds; it varies in pines ee 
Color, but it is generally found of a light buff color Wi i 
grained. It is not intended that it should be understood tha 
the mass of m always rests upon, and is always the A 
tock of, the Cavernous limestone of the district ye : 7 
On the contrary, the second sandstone 1s pike erg ithe 
masses of J and m being both absent. This is the case at the 
mounty, to Hopkinsville, Christian County, Kentucky, the 
mass of d of our section is found, at one ee resting on t 
ria iles to 
it rests being the equivalent (?) of the beds found 60 miles 
the Northeast from this an a Hardin County, from 275 to 
