xt73r20rrd2h https://exploreuk.uky.edu/dips/xt73r20rrd2h/data/mets.xml Kentucky. State Geologist. 1882  books b97-20-37305592 English Yeoman Press, : Frankfort, Ky. : Contact the Special Collections Research Center for information regarding rights and use of this collection. Geology Kentucky Garrard County.Linney, W. M. (William M.) Report on the geology of Garrard County  / by W.M. Linney. text Report on the geology of Garrard County  / by W.M. Linney. 1882 2002 true xt73r20rrd2h section xt73r20rrd2h 











GEOLOGICAL SURVEY OF KENTUCKY.

         JOHN R. PROCTER, DIRECTOR,



                  REPORT


                    ON THE


GEOLOGY OF GARRARD COUNTY.



BY W. M. LINNEY.



STRREOTYPED FOR THE SURVEY BY MAJOR, JOHNSTON  BARRETT, YEOMAN PRESS, FRANKFORT, KY.

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INTRODUCTORY LETTER.



HON. JOHN R. PROCTER,
               Director of the Kentucky Geological Survey:
  DEAR SIR: I have the pleasure of transmnitting to you my
Report on the Geology of Garrard County, accompanied by a
mapvand profile section.t
  Owing to questions involved in the physical history of this
region, I extended the profile section beyond the county, so
as to include Mercer and a part of Rockcastle. This exhib-
its a continuous section of sixty miles, which illustrates the
relation of the formations better than one limited to Garrard
county
                         I am, very truly, yours,
                                      W. M. LINNEY.
 HARRODSBURG, Ky., December, i882.

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GEOLOGY OF GARRARD COUNTY.



                     TOPOGRAPHY, &C.
  Garrard county dates its organization from I796, in which
year it was formed from parts of Mercer, Lincoln, and Madi-
son. It is situated near the center of the State and has
Jessamine and Madison on the north. Madison and Rock-
castle on the east, Lincoln and Rockcastle on the south, and
Lincoln, Boyle, and Mercer on the west. Its area comprises
about one hundred and thirty-four thousand acres of land;
and, in i88o, it had a population of eleven thousand seven
hiundred and four, having increased from ten thousand three
hundred and seventy-six in the previous decade.
  Lancaster, with one thousand two hundred and thirty-four
inhabitants, is the county seat and the largest town. A
number of villages and post-offices are scattered over the
county. The boundary line is a very irregular one, being
marked nearly all around by the sinuosities of creeks and
rivers. The Kentucky river flows for some distance along
its northern boundary. On its tides are brought down con-
siclerable quantities of coal and lumber-of which a part only
supplies the citizens. Dix river flows along the western por-
tion of Garrard, and furnishes fine milling facilities. Paint
Lick, Boone, Sugar, and other creeks meander through the
county, giving good drainage lines, and affording additional
sites for a number of mills, some of which are already util-
ized.
  All the drainage of the county flows into the Kentucky
river; but the characters of the streams in various parts of the
county are quite different. The northwestern part of the

 


GEOLOGY OF GARRARD COUNTY.



county lies in an angle made by the Kentucky river and Dix
river. Here those streams flow in canon-like valleys four
to six hundred feet below the higher parts of the surface.
Narrow chasms,- with almost perpendicular walls of solid
rocks, from two to four hundred feet in height, are their char-
acters; so narrow are the valleys, and so steep the escarp-
melnts, which rise frequently to the level of the country, that
a stranger often finds himself on the brink before he is aware
of his proximity to a river. Sometimes the surface even
slopes back-from the tops of the cliffs. The small streams
which enter the rivers here have the same character of val-
leys. Under such conditions, one would expect to find a
number of cascades in ascending their channels. This, how-
ever, is not the case to any extent; for while their fall is
hundreds of feet in a few miles, yet this fall is so regularly
distributed along their flow that they enter the rivers at their
ordinary levels.
  The only explanation of this fact is, that along this region
the Kentucky river and Dix river flow inl channels, which
were originally open fractures in the crust of the earth, and
that the small streams run in side fissures from these old frix-
tures, and erosion has removed the broken material so regu-
larly that, while the fall is rapid, no great benches are left.
Through this part of the county there are lines of subter-
ranean drainage, whose origin is intimately connected with
the open fractures above described. These lines under the
ground are marked on the surface by holes and depressions,
into which the waters sink, only to reappear at some distant
points as springs.
  There are a number of fine bold springs in this regic,:-z
yet they are rare as flowing immediately from the cliffs along
the rivers. They are oftener found on or near the smaller
branches, and are always connected in some way with thl
fractures and dips of the rocks. Usually the dip is away
from the river onl each side; this prevents the flow of spring
waters directly into the streams, and causes them to issue
further back in the country.



6

 

GEOLOGY OF GARRARD COUNTY.



  The water here is of the best potable character. The bot-
tom lands along the streams are only little narrow patches,
and are composed of materials which have been brought
down by the rivers' action, and deposited in protected places
over the talus from the cliffs. There are many striking views
among these wild and picturesque cliffs. Massive and strong,
thcy rise ill smooth walls or broken ledges, with here andc
there some scrubby tree or clinging vine mantling the rocky
walls, which are seamed with many a fracture, and pictured
with many a stain. Sometimes overhanging walls, with beet-
ling brows and buttresses bare, shade the flowing stream
beneath. Chimney-rocks stand away from the line of walls,
isolated and gray, and look as if reared by human hands. It
is doubtful whether the famed Hudson has so many admi-
rable scenes along its banks as the Kentucky.
  Such is the character of these streams which bound the
county up to the mouth of Cooper's Branch. In going up
the river from this point the cliffs begin to diminish in height,
and their walls to disappear, until, in a few miles, the perpen-
(licular rocks give way to sloping hills, which are rounded to
the water's edge. The creeks, which enter along and above
this point, have their channels between steep, sloping hills
of the last mentioned character. The rocky escarpments
seen below have, by a rapid dip, been carried under the
drainage lines, and softer rocks, more easily eroded into
curved lines, have taken their places. On the opposite side
of the county, Boone and other creeks partake of the same
description ; and, while cutting into the strata hundreds of
feet, they are flanked by productive soils, extending down to
the bottom from the highest points of the hills.
  As one goes further to the southeast he finds a number of
streams, whose beds are but slightly beneath the general sur-
face. Their flow is not of the rapid character of the others.
The surface of the county is more gently rolling, and, as
agricultural land, more agreeable to the eye. Further to the
southeast is a series of hills, several hundred feet high, ele-
vated above the general surface, with steep declivitihs, be-



7

 



GEOLOGY OF GARRARD COUNTY.



tween which are small branches that cut down rapidly here,
but afterward flow gently through the more level country
beyond.
  The Kentucky river, during the season of high water, is
navigable for steamboats along its entire length in the county,
yet for some years none have passed up. The improve-
ments now being erected in the river in the way of locks and
danls will in time be extended to this county and above, thus
making navigation continuous through the year. This will
be of great convenience to the people of the county. The
Kentucky Central Railroad -extends through the county, and
gives good facilities for all travel and shipments. The Cin-
cinnati, New Orleans and Texas Pacific Railroad (Cincinnati
Southern) is within easy reach, by several good roads, from
the county.


                 GENERAL GEOLOGY.
  The stratified rocks of Garrard county, in their connected
exposures, have an aggregate thickness of over, seventeen
hundred feet of palaeozoic strata, ranging from the Lower
Silurian to the Subcarboniferouls Limestones. There is, per-
haps, no county in the State whose geological features are
more interesting to the student; for here lies in part the key
to problems which bear not only upon the general geolog)
of the State, but reach beyond its outlines, and include points
of interest in other States. The following is a general group-
ing of the various outcrops in the county, as traced from one
exposure to another; they are arranged under the general
names which such rocks usually bear in the United S-tates.
It may be stated here that the thickness and general chlar-
acter of these groups are, in a large measure, very uniform
over the region surrounding Garrard county, as far as they
appear on the surface. They are open to the investigation
of the geologist at many points:



8

 


GEOLOGY OF GARRARD COUNTY.



   SoWLS AND WASTE BEDS.                           Feet.  Feet.

Carboiferous--
Subearboniferous Period.... Upper.... . .. .. .. . .   20     320
                          Lower.                    300  

Devonian-
Hamilton Period..... . . Black Slate.......... .       ....    50

('orniiferous Period.(orniferous ....         .  .              15

(rpper Silurian-
Niagara Period....... . Clinton ....... ... .1                     0
                          Medina .......... . .

Lower Silurian-
Trenton Period .Hudson River .6....... . 50
                          Trenton.... . .. .. .. .   160
                          Birdseye.  . .. .. . . .

 Canadian Period.......  Chazy... ....                      3f50

    Total.... .. .. . .  . .. .. .. . .. .. .. . .. . ..   1, 7:Z



These divisions



are based upon



the more remarkable



chalnges in the composition and appearance of the rocks.
Such changes make many marked differences in the character
of the soils, and in the distribution of trees and smaller plants.
They also modify largely the general appearance of the coun-
try as to levels and slopes  Another and very important
element, which serves to separate these groups. is the char-
acter and forms of the fossils. These distinctions have been
made by geologists for the convenience of study and descrip-
tion. Rocks which appear to be the samne to the superficial
observer are often found in each of these (livisions; but the
more practiced eye distinguishes themn by certain characteris-
tics at a glance.
  The above thicknesses are approximate only, for it is very
difficult in such a section, extending across an eroded region
like this, to get accurate measurements of all the rocks.
Measurements were made in some cases with an aneroid



9

 


GEOLOGY OF GARRARD COUNTY.



barometer, and in others, when practicable, with a rule or
line.

              THE CANADIAN PERIOD.
  The Chazy Limestone.-On the Kentucky river, at or
near the mouth of Cooper's Branch, the lowest rocks brought
to view in the State are to be seen. In their natural expos-
tires, and in their superficial characters, they have a general
resemblance for an elevation of three hundred and fifty feet;
but at that point some ten feet of rocks, quite different in
appearance, and also in chemical character, are brought to
view. These three hundred and fifty feet of strata have
been determined, from their position and other circumstances,
to be in part the equivalents of the Chazy Limestones, a
series of rocks first described and named as occurring at
Chazy, in the State of New York.
  They are here composed of a number of layers of very
heavy-bedded rocks, compact in their structure, and usually
quite tough, when tested under the hammer. They are of
various colors-some are gray, some bluish, others of a dove-
color, and even lighter. The most of them, however, have a
mottled appearance, when closely examined, on their exposed
surfaces, or when freshly broken. Of these, the base is a
dark dove-color, with spots of dull yellow, which are rather
sandy in their nature, and are the impressed remains of a
class of sea-plants that grew in the ocean when and where
these. rocks were formed. Among these are the remains of
shells, corals, and other forms of life; other layers have been
largely made from shells alone, and some of them show onl)
casts, while branching corals make up a large part of the
whole. Often these have leached out, leaving the outer
surfaces of the layers honey-conmbed with curious, tortuous
holes. Some of the beds are close and fine-grained, and the
structure of the old fossils is entirely obliterated, or their
presence marked only by the faintest lines.
  In composition, these rocks are mostly lime, but nearly all
of them contain some silica, magnesia, and earthy matters.



to

 


GEOLOGY OF GARRARD COUNTY.



Sometimes a little shaly or carbonaceous matter intervenes
between the layers, though the proportion of this is quite
smiall. Many of these rocks are well fitted for buiilding pur-
poses, being very tough, and resisting decomposition in a
remarkable degree. Lime of an excellent quality can be
burned from them. As yet, their use for these purposes is
entirely local.
  Ini wall-like cliffs, where only these rocks are shown, there
is much difficulty in examining them for fossils; besides, the
changes to which they have been subjected, have in a large
measure destroyed the forms, or, at least, the finer lines of
identification; so that, in most cases, they are rendered
worthless as specimens, either for the cabinet or for critical
determination.
  Fortunately, however, a few places give a sufficient num-
ber of forms by which these rocks have been identified, and
placed, at least the upper part of them, in the Chazy Lime-
stone. The lower portion may in time be shown to belong
to the Quebec group.
  The upper portion of these strata contains numbers of a
large coiled shell, the llac/urea magna, and, at about sixty-
five feet below the top, a few thin layers yield numbers of
Orthis costa/is. Besides these forms, there have been found
Rhynchone/la f/ena, Asaphus marTina/iq, Leperdilia Canadensis.
with some other fossils, which, with its position and relation
to the upper groups, identify it, without doubt, as. the equiva-
lent of the Chazy.
  This series of rocks is seen only along the gorges in this
part of the State, and is lost beneath the drainage' lines,
both up and down the river. They give, therefore. 1.o soils,
for they do not rise to the surface of the. uplands; yet, in
their massive ruggedness, I they add wild and picturesque
features to the streams which flow between them, and are
interesting as the oldest and lowest rocks seen in the State.
At the m6uth of Dix river they are over two hundred feet
above the water; in ascending that stream, they sink beneath
it at Green's old mill. In going up the Kentucky, from the



I I

 

GEOLOGY OF GARRARD COUNTY.



mouth of Dix river, they rise, as we have stated, to three
hundred and fifty feet at Cooper's Branch, and are lost to
view three miles above.

                  TRENTON PERIOD.
  Birdseye Limestone.-Succeeding the Chazy Lime-
stones is first seen the ten feet of rocks to which reference has
been made. This is often termed the "Kentucky marble,"
and it has been used to some extent in the State, notably, as
the material of the Clay Monument at Lexington and of the
columns of the State-house at Frankfort. It averages about
ten feet in thickness. On exposed surfaces it is buff in color,
but ,internally it has a gray ground, with blotches of blue,
which near the surface often change to a brown. There are
no fossils in it; yet it is evidently part of the Trenton, as, in
New York, and also at one or two points in the northwest, a
buff limestone of near this thickness makes the base of the
Trenton. It is a magnesian limestone, containing usually
thirty-five to forty per cent. of magnesia.
  Succeeding this magnesian limestone is one hundred and
twenty feet of limestone, the larger part of which is of a
light or a dark dove-color, brittle, heavy-bedded, and fine-
grained. Shale is formed between some of the layers, and
some thin limestones in the shale. Many beds are of suLch
quality that they would make handsome building stonles.
Impressions of plants ramify through many of them, and
quite a large proportion show strings of lime crystals irn-
bedded in them. The impressions in some of these layers
have the identical character of a plant figured in the reports
of the State of New York, and described as Phyfopsis tubui-
losa. The worn or ground surfaces have round crystalline
spots which to some extent resembles the eyes of birds, hence
the name Birdseye Limestone. Some of the layers show the
lamination perfectly when worn in their natural exposures, and
are susceptible of being split into slate-like pieces. The
shales are quite earthy, nearly white, and seem to have been
deposited as fine clay sediment.



I 2

 

E01:OI.(GY OF GARRARD COUNTY.



  Near the top are several layers, containing masses of
hornstone, which give them a rugged aspect when worn, the
lime having leached away from around the chert, and left it
protruding from their sides or tops. The top layer is plated
everywhere with a reddish hornstone from one to three
inches in thickness.
  Evidences through all these rocks show, that while the
materials of which they are composed were being laid dowvn
on the bottom of the old ocean, life existed abundantly in
many forms. Scarcely a fragment can be examined which
does not show markings of organic life; yet, from, subsequent
changes made in this series here, few of these remains have
been so preserved as to make their determination as certain
or definite as we would like.  Little crustaceans of the
genus Leper-ditia are wonderfully numerous; Bryozoa are
equally so. Some corals and shells have been identified with
enough certainty to enable us to determine the' position of
the beds.
  These rocks have but a limited distribution away from the
rivers mentioned, and give, therefore, little soil. Fine quar-
ries might be opened in them at a number of places, and
beautiful building stones secured. Some of them are suscep-
tible of a fine polish, and a few are fine enough for litho-
graphic stones, but for some minute specks of iron and lime
which they contain.
  Trenton Limestones.-Succeeding the last mentioned
rocks are seen about one hundred and sixty feet of mostly
thin blue and gray limestones, with thin beds of shale often
between them. These might, with great propriety, receive
the name of "Blue Grass" beds, for they are preeminently
the rocks upon which that richest and best of grasses thrives.
Their rapid decomposition furnishes the best of soils, and
they outline and define the most beautiful and most highly-
prized part of the State. In Garrard they are confined to the
northwestern part of the county.
  The superficial character of these beds ha often con-
founded them with another group, which lies higher in the



I 3

 


GEOLOGY OF GARRARD COUNTY.



geological scale. They are generally of a light, gray color,
and are massive in the fresh quarries, and at some distance
from long-exposed surfaces; but, with few exceptions, they
wear thin-bedded after long exposure. Near the base there
are several strata which have a large amount of cherty matter
included in them. Near the top are some heavy layers also,
more than half crystallized, and sometimes with a pinkish
tinge. The shales are soft and of clay, and are in small
proportion to the mass. Through the whole series there are
no good building stones, except near the top, and in this
county these have not been put to any use. Just at the top,
tlhere are twelve or fifteen feet of fine-grained dove-colored
stones, heavily bedded, which, from their resemblance to the
lower group, I have characterized as the Upper Birdseye.
Their extent in Garrard is very limited; they will be de-
scribed more fully in the report on Mercer county, where
they are seen to a better advantage.
  The greater part of these rocks decomposes rapidly, owing
probably to there being more or less earthy matter in them.
Fences are often constructed of stones from these layers,
which look very well when first put up; but in a few years
they melt down into soil.  Some beds are composed of
branching corals almost entirely, and in their decomposition
these are liberated in great quantities. In the lower layers,
where the chert is seen, many of the fossils are silicified, and
hence are better preserved. Or/his testudinaria, Or/his Pec-
tine/la, Or/his tricenaria, Lepahna sericea, Pe/raia aperla,
Streptelasma profundum, and a number of other forms, are
common in places.
  These rocks are in great contrast with the Birdseye Lime-
stone below in colors, bedding, and fossils. The conditions
of the old ocean, in which they were deposited, must have
undergone great changes. The former must have been
deposited in deeper, clearer water, where the surroundings
remained unchanged for long periods of time; the latter,
where the Water was more shallow, and the currents brought
in quantities of earthy sediments. Oscillations must have



14

 


GEOLOGY OF GARRARD COUNTY.



occurred at times, for some of the. layers are very irregular
in their bedding; some show wave-marks, and others a beach-
like structure.
  The whole series terminate with the heavy layers of Up-
per Birdseye filled with great number of Leperdilia, and with
a few thin beds of concretionary limestones, marked with a
small form of Orthis lynx, Orthis borealis, Rhynchonella ilcre-
bescens, &c. Very often, too, are seen masses of a large
coral, Stromatopora rugosum, and some rounded pebbles,
which mark a period of change at this time. All these beds
of the Trenton are carried down by a steep dip to the south-
east, which soon brings the Hudson River Group on a level
with that of the Trenton.

              HUDSON RIVER GROUP.
  WVe come now to the consideration of a great and impor-
tant group of rocks, which covers a considerable portion of
our State, and extends unbroken into Ohio and Indiana, and
whose proper correlation and position may solve a number
of problems of unusual interest connected with the States
lying in the Ohio Valley.
  They are from six hundred and fifty to seven hundred feet
in thickness in this part of the State, and have received the
name of "1 Hudson River Beds," in the Reports on the Geol-
ogy of New York. In that State, they are divided into
three divisions-the Utica slates, the Lorraine shales, and the
Oswego sandstone. They are here conveniently separated
into three series by the differences, which are well marked in
the rocks themselves, and also by the soils which are derived
from them.

  Lower Hudson River Beds.-This division has a
thickness of about two hundred feet in the county, and begins
at the base with a few layers of blue earthy limestones, coiii-
posed largely of two species of branching corals. There is
a layer of crinoidal limestone that comes in between those
beds, which is quite hard, and contains much less clay. Next



1 5

 


GEOLOGY OF GARRARD COUNTY.



is seen a considerable thickness of clay shales, with thin
plates of limestone intercalated, and above heavier limestones
with the proportion of shales much reduced. The rocks of
this division make but few exposures in the county that can
be seen to any advantage, being usually covered with vegeta-
tion, or, if the areas come to the surface, being cumbered
with loose stones, so that their character has had to be
studied to some extent in contiguous counties, where good
sections can be examined. The great wave-marks, which are
a curious feature of the upper part of these beds in Mercer
and Washington, are seen in Garrard wherever their horizon
is exposed.
  Their position here places them with the lower beds,
exposed at Cincinnati. The shales and limestones are very
similar in character to those at that place, while the ranges
of fossils are so much alike that their identity is unquestioned
by those who have carefully examined -both regions. They
do not fully answer to the descriptions of the Utica shales in
New York; but enough facts have been elicited to demon-
strate that, in part, at least, they hold the same position in
the series.
  The soils given by these beds are of a heavy clayey char-
acter, and are usually covered with large fragments of the
limestones which are included in their upper strata. These
soils are very limited; they extend only in a narrow strip
across the county, from northeast to southwest, in an irregular
curve, and are otherwise seen only in the. lower part of some
of the drainage lines which have cut into them. Full consid-
eration is given them in the reports on Mercer and Washing-
ton counties.

  Middle Hudson River Beds.-Superimposed on the
foregoing division of rocks is one hundred and fifty feet of
sandstones, shales, and a few intercalated beds of impure lime-
stones, called in the old volumes of the Kentucky Reports
"Silicious Mudstone."  The sandstones are not hard grit as
many other sandstones are; but, on the other hand, they are



i6

 

GEOLOGY OF GARRARD COUNTY.



quite soft, and contain a large per cent. of clay, with more or
less silicious and calcareous matter. Some of them are, how-
ever, to be ranked as sandstones, being heavy-bedded, and
to some extent gritty. The shales are of much the same
order, but thinner-bedded, and hence more easily decom-
posed. The whole thickness is easily reduced to soils, and it
is not often that one can see a section where their general
characteristics may be studied.
  Some of the sandstones harden on exposure, and have
been used for building fences, chimneys, &c. They break
out very irregularly in the quarry, and are not valued where
other stones can be procured. Their exposed surfaces are
of a dull yellow color; but, when seen fresh in a quarry, they
are blue, as are the shales imbedded in them. There are in
this series usually two layers quite heavily-bedded, which have
a concretionary structure, and wear often into great bowl-
shaped masses, which are very peculiar. The beds of lime-
stone on exposed faces are rather of an olive color, and split
into thin flaggy layers. They usually show, when thus split,
some dendritic markings. The sandstones and shales are
often stained with thin, black, shining incrustations, due to
oxide of manganese. Many of their surfaces are covered
with the impressions of plants, and the casts of shells, corals,
and trilobites are common throughout.
  Many of the soils of the county are based on these rocks,
notably those on Sugar creek, Scott's Fork, and Boone's
creek, and are highly esteemed as corn lands. The decom-
position of this series is rapid and deep; and, although the
soils are washed off by rains, this fact is hardly noticed, for
another turning by the plow leaves them as fresh as ever.
The drainage lines have cut into them very deep, and the
slopes are very steep. The whole thickness is often seen in
the side of one field with the Lower Hudson beds at the
base. The farms are here cultivated, with hill-side ploughs,
where the slopes approach to forty-five degrees. I was in-
formed that some fields had been, for fifty years or more,
annually cultivated in corn, without apparent injury to them
    GEOLO4G. SUR.-)



I 7

 

GEOLOGY OF GARRARD COUNTY.



  The preservation of so much of this division of rocks,
with their soft character, is due to the fact that they lie in
a trough-like depression, the KENTUCKY SYNCLINAL, which
includes more than one half the length of the county.
  There are not many springs that flow from these rocks, and
the water is not of an excellent character, being impregnated
with earthy salts, sometimes to an injurious extent. The posi-
tions of these beds are those of the Lorraine shales of New
York, and in part of the Eden shales of Cincinnati.

  Upper Hudson River Beds.-The upper part of the
Hudson River Group is not so uniform in its general charac-
ter as the several series so far described, yet sufficiently so to
be retained as one division. It comes in at the base with
a number of feet of thin, shelly, blue limestones, which are
usually very uniform in appearance, having always their thin
partings of shale. These layers are extremely rich in fossils,
and form the second best soils in the State. At this horizon,
and confined to a limit of less than one hundred feet of rocks,
there is an assemblage of fossils, many species of which are
not seen at any other horizon, but which mark a position that
can be observed in a number of contiguous counties. These
fossils are in part Pti/odic/ya hi/li, P/ilodid/ya falciformis, Catrlo-
ceras va/landiflghami, Or/his linneyi, Re/epora angulata, Con
chico/i/es corruga/us, Sireptorhynchus p/ano-conzvexus, Prota;r-e
ve/usta, Stelzipora antheloidea, Chae/etes or/ooni. Above these,
and ranging through the rest of this division, are the beds of
-Orthis lynx, with its numerous varieties, associated with a
number of other well-known forms found through the \Vest
at this horizon. A number of heavy layers of earth)y lime-
stones, barren of fossils, or only preserving them as casts,
are associated above them.
  Near the top are layers of what has been termed by Prof.
N. S. Shaler, the "Cumberland Sandstone."   The color is
usually a blueish-green, but weathering to a yellowish-green
on the outside. It contains some silicious matter, but is
largely argillaceous in its composition. This is its character

 

GEOLOGY OF GARRARD COUNTY.



in Garrard, but in other counties it is more sandy. In a
freshly opened quarry it promises to make a fine durable
building stone; it is, however, worthless as such, for, on
exposure, it breaks up into square blocks, and soon crumbles
into soil. There are, however, several layers of beautiful
limestone, six to ten inches in thickness, found in these beds,
which make excellent stones for building purposes.
  These beds all make fair qualities of soil, and have a wider
exposure than any other group of rocks in the county; and,
while nowhere very level, they are the most gently rolling
lands in the county. T[he potable water which issues from
these rocks, especially from their lowver part, is very good.
The whole thickness is something over three hundred feet;
but the dip of the series and the exposures, where a good
section of any part of it can be seen, are few.
  There are a number of places where these soils have
been allowed to become badl) worn under a poor system of
ploughing and grazing. Those places are generally based on
the clay soils, which do not hold together very well in dry
weather, but crumble down when exposed to the air. On the
other hand, they do not form over them a very close sod, and
in a wet season, heavy stock tramping on the hillsides are
apt to cut through it with their hoofs and start washes, which,
if not soon repaired, create bad places in the fields or pas-
tures.
  The top of these beds and of the Lower Silurian is marked
il places by an irregular mass of limestone, which is filled
with large corals of the genus Columnarina, and associated
with those are many other forms, such as Te/radium, Strep-
telasma, &c.; but often the Cumberland Sandstone is at the
top, making it difficult to determine the dividing line be-
tween it and the next.

                   UPPER SILURIAN.
  The rocks of the Upper Silurian in Garrard amount only to
a thickness of some sixty feet, and have at the base thirty-
five feet of sandstones, which are the probable equivalentq



I 9

 

20GEOLOGY OF GARRARD COUNTY.



of the Medina sandstone of New York. The greater part
of this is a soft, easily pulverized sandstone, sometimes con-
cretionary, containing in places some layers which have been
used for building purposes. They quarry very easily, and in
good well-shaped blocks. They are of a dull yellow, but are
much lighter in color than the rocks from the middle beds of
the Hudson River in other parts of the county. They harden,
when placed above drainage, and become very durable.
  The soils derived from these rocks are sandy and easily
eroded, consequently one sees many sterile spots in the parts
of the county where they exist. They are be