xt7qrf5k9x5d https://exploreuk.uky.edu/dips/xt7qrf5k9x5d/data/mets.xml Norwood, Charles Joseph, b. 1853. 1877  books b96-12-34887942 English Stereotyped for the Survey by Major, Johnston & Barrett, Yeoman Press, : [Frankfort, Ky : Contact the Special Collections Research Center for information regarding rights and use of this collection. Lead Kentucky. Geology Kentucky. Reconnoissance report on the lead region of Henry County  : with some notes on Owen and Franklin counties. text Reconnoissance report on the lead region of Henry County  : with some notes on Owen and Franklin counties. 1877 2002 true xt7qrf5k9x5d section xt7qrf5k9x5d 










GEOLOGICAL SURVEY OF KENTUCKY.
        N. S. SHALER, DIRECTOR.



   A RECONNOISSANCE REPORT

               Off TM

LEAD REGION OF HENRY COUNTY,



           WItH SOU NOre ot

OWEN AND FRANKLIN COUNTIES,

     BY CHARLES J. NORWOOD.

     PART VII. VOL. II. SECOND SERIES.



24S & 246

 This page in the original text is blank.

 















             PRELIMINARY LETTER.


Professor N. S. SHALER, Director Kentucky Geological Survey:
DEAR SIR: I herewith submit to you a report of a recon-
noissance made in the lead district of Henry county, during
the month of May, i875.
I trust that it may be found of service to all interested.
                   Respectfully yours,
                         CHARLES J. NORWOOD.
 LEXINGTON, Ky., December ist, i875.
                                                    247

 







  A RECONNOISSANCE REPORT ON THE LEAD
      REGION OF HENRY COUNTY, WITH
          SOME NOTES ON OWEN AND
               FRANKLIN COUNTIES.


                            1.
                  HISTORY OF THE MINS
  The existence of lead in Henry county is not a recent dis-
covery. It is a well-assured fact that the deposits attracted
attention as far back as i8i5, and perhaps even at an earlier
time.
  There is a legend current that silver also was found; this,
however, is simply another instance of that delusion so com-
mon to all mineral districts, or even in regions having no
metalliferous deposits. Those who tell the tales are, usually,
thoroughly honest in their belief, however great may be their
mistake. The story concerning the silver of this county grew
from the fact that, some thirty-five or forty years ago, a family
bearing the name of Knight, which lived on Drennon Creek,
and occupied a cabin on the land then belonging to a Mr.
Minor (now the property of Mr. S. Loudon), conducted them-
selves in such a manner as to bring them under suspicion of
secretly coining money.
  The story is, that persons journeying in the neighborhood
at night would see bright lights in the house even at mid-
night, the house being so illuminated by flames, which were
supposed to issue from a furnace, as, at a distance, to appear
"all ablaze." The Knights, however, received warning of
the traveler's approach from their dog, and the house would
be darkened before it could be reached.
  Finally, suspicion increasing against them, they were driven
from the county. After their departure several pars Of
245

 

LEAD REGION OF HENRY COUNTY.



money moulds were found where they had been secreted in
the woods, and, as the relater believed, near their old cabin.
  This was accepted as conclusive proof that Knight had
been engaged in making silver money, and that the silver
was found in the immediate neighborhood.
  So far as the supposition that Knight coined money is
concerned, the legend is doubtless correct; that it was silver
money, however, is not so well proven.
  It seems simply to have been an instance of counterfeiting,
the place being selected for the operation on account of its
seclusion.
  The absurdity presented by the statement that the metal
was silver should be apparent to any one. Had it been that
metal,it would have been a mere waste of labor and ingenuity
for Knight to have done the coining, as the silver could have
been exchanged at the Government Mint for its worth in dol-
lars already coined.
  This matter has been given greater prominence than would
have been due to it were it not that many, both in and out of
the county, have an abiding faith in the existence of a "' silver
lode " in the county, and entertain notions of searching for it.t
All search for the metal will prove futile, and it is simply an
utter waste of time and of money to prosecute it.
  The oldest " digging," so far as could be ascertained, is
on Mrs. Eliza Ann Green's farm, about two and a half miles
eastwardly from Franklinton and eight miles from Lockport.
Excepting a number of fragments of limestone which are scat-
tered near by, all signs of the digging have disappeared, the
excavation having become filled level with the surface with
debris washed down from the hillside. A few years ago, how-
ever, the pit was only partially closed, sufficient yet remaining
open to show that the opening was about Io feet square.
MIrs. Green states that the pit was opened about 6o years
ago, before the place was cleared, the land then belonging to
  it i, said that a man named Margo also coined money.
  t ndeed, I noticed in one of our county papers, published in May of the present year, a
letter from a gentleman professing strong belief that a silver lode is to be found in Henry
00unty, and to a certain extent urging that it be searched for.
                                                           249



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A RECONNOISSANCE REPORT ON THE



a Mr. Cook. It is presumed that the digging was done by
the settlers in order to procure lead for domestic use. This
is, doubtlessly, the correct view of the matter. Other pits
were subsequently opened in the region at various times to
procure the mineral.
  In 1823 or i824 a Mr. Suckett opeled a pit on Jas. Roberts'
place, where the II Silver and Spar" mines are now located; it
was merely a "prospect hole," and nothing of consequence
was done. This pit, so far as could be learned, stands next
in age to that on Mrs. Green's land.
  The next record we have of any mining was in I 825 or i 826,
at which period a Mr. Ficklin mined on Big Twin Creek, in
Owen county, at Flannigan & Hunter's Mill. A period of io
years then succeeded in which no new developments seem to
have been made.
  In I836 Messrs. Perkins and Little (from Shelby county, it
is believed) erected a furnace on the site of the present " Sil-
ver and Spar" mines, and smelted a small amount of lead.
The works were on quite a modest scale, and were operated
for only a short time.
  Three years later, in x839, two men, Messrs. Barbour and
Waggoner, had a pit sunk to a depth of about 50 feet on the
McCrell place, in Owen county, then known as Meach's bottom.
  About fifteen years ago, perhaps not quite so long, quite an
excitement prevailed for a while concerning the lead depos-
its, and considerable was done in the way of either buying or
leasing lands for mining purposes. After a few excavations
were made, however, the excitement died away, or rather
slumbered to be renewed at intervals up to the present time,
when it has, perhaps, attained its greatest degree of energy.
  For an interval, however, extending from i839 or 1840 to
1865, no openings of much consequence were made. No reg-
ularly organized plans were formed for working the deposits
until about i865 or i866.
  This is in accordance with what information could be gathered at the time. Much
trouble was experienced in the effort to get at the history of the: mining operations, as many
of those who were supposed to know had, with the exception of Mr. Raser (to whom I a-,
indebted for much of i sketch), very imperfect memories as far as regards this matter.
sp



6

 


LEAD REGION OF HENRY COUNTY.



About the year i865 a company from Wisconsin opened
pits on farms belonging to Mr. Wallace and Mr. Roberts, near
Lockport, and also leased or bought the right to mine on the
farm of Mr. Aris James, which is about one mile in a west-
wardly direction from the village. A larger amount of work
was done on the latter place than on the farm of either Mr.
Wallace or Mr. Roberts. Nothing of consequence resulted
from it, however, and after a number of shallow pits had been
excavated, the spot was abandoned, and has so remained to
this time.
  At about the same period an organization known as Stew-
art & Company gained possession of the openings on James
Roberts' place (" Roberts' Landing"), hitherto mentioned.
They were succeeded by Parker & Company, a Philadel-
phia company, who in turn were succeeded by the present
owners.
  Not, however, until within the past two years has any
mining been done on an extended plan. In 1873, or about
that time, a company, incorporated under the name of the
"Silver and Spar Mining Company," assumed charge of the
mines-or more properly diggings-at Roberts' Landing, as
already intimated.
  Little work was done, however, until about one year ago-
in the spring and summer of 1874-since which time the work
has been carried forward with considerable rapidity. These
mines are the only ones properly deserving the name in the
county. In 1874 a shallow pit was dug in near proximity to
Drennon Lick by Messrs. Hardin and Hurl; but very little
more was done than sinking the shaft.
  This brings the history of the mining down to the present
year, during which period, at least not anterior to June ist,
when the region was examined, no new openings have been
made.
  Although somewhat incomplete as a detailed history, this
sketch is believed to be as nearly correct and comprehensive
as can now be obtained.
                                                       251



7

 


A RECONNOISSANCE REPORT ON THE



  The several localities already mentioned are treated of in
more detail on succeeding pages; and, in addition, a number
of diggings that are not mentioned here are discussed.
  As a matter of interest and of instruction it would be well
to have a trustworthy account of the amount of money that
has been expended on the lead deposits of this county from
I815 to 1875, without the return of a dollar of actual profit;
unfortunately, however, no data for this computation can be
had.
                            II.
              GEOLOGY OF THE LEAD REGION.
  The sub-structure of this lead region is formed of Upper
Cambrian rocks, their precise age, however, being somewhat
obscure.
  Fossils that in other States are considered typical of the
Hudson River and of the Trenton Groups are here found
together, and ranging almost throughout the series. The
paleontological evidence would point to the identity of these
rocks with both of the groups above named, but the mingling
of the forms prevents the location of any definite line of
separation. They certainly are, in part, of the same age as
the Cincinnati Group, and the most pleasing solution of the
question regarding their age is to consider them equivalent
in part to the Hudson River Group, merging into Trenton
beds below.
  Dr. Newberry, in volume I, part I, of the "' Final Geolog-
ical Report on Ohio," gives as his reason for retaining the
name "L Cincinnati Group" (given by Meek and Worthen) for
the series of limestones and shales of which the rocks in this
district form a part, that the group is equivalent both to the
Hudson River and Trenton Groups, of New York, and not, as
some have believed, because the term " Hudson River Group"
was a misnomer; later investigations prove it to have been
correctly applied.
  As the rocks in this district are, without doubt, near the
base of the Cincinnati Group, they probably include, towards
2S2



8

 


LEAD REGION OF HENRY COUNTY.



their base, beds equivalent to the Galena limestone of Illinois.
It may, therefore, be provisionally accepted, until more definite
knowledge is gained concerning them, that the rocks in this
district include equivalents of the Galena limestone, with Hud-
son River beds at the top.
  Professor Whitney's description of the Galena limes/one
(which lies next below the Cincinnati Group) is as follows:
",The Galena limestone, as usually developed, is a rather- thick-
bedded light grey, or light yellowish-grey dolomite, distinctly
crystalline in texture, and usually rather granular, although
occasionally quite compact. The coarse-grained portions fre-
quently contain small cavities of irregular shape, which are
often lined with minute crystals of brown spar. In its chemical
composition this rock is quite homogeneous; it is almost a
pure dolomite, since the various analyses which have been
made show it to contain only from two to five per cent. of sub-
stances insoluble in acid (clay and sand), while the remainder
is a mixture of carbonate of lime and magnesia, in the propor-
tion necessary to form dolomite (carbonate of lime 54.35, and
carbonate of magnesia 45.65 per cent.), with one or two per
cent. of the carbonate of the protoxide of iron, which be-
comes gradually peroxidized on exposure to the air, and traces
of the alkalies, chlorine, and sulphuric acid.        The
upper layers of the Galena limestone are usually more regu-
larly and thinly bedded than the middle and lower.   At
the very summit of the formation the rock is quite shaly and
argillaceous, indicating a passage into the Cincinnati Group
above.   The middle portion of the Galena limestone
is usually very heavy-bedded, crystalline, and marked by
an abundance of flints arranged in parallel layers.   
The maximum thickness of the Galena limestone, where none
of it has been removed by denudation, is from 250 to 275
feet."
The limestone, which in this region is supposed to be the
equivalent of the Galena limestone, does not answer to the
foregoing description in every respect. An analysis, made in
                                                         2S3



9

 


A RECONNOISSANCE REPORT ON THE



the laboratory of the Survey, of samples taken from near the
Silver and Spar mines, shows its composition to be as follows:

Carbonate of lime. .  .       ............               95 770
Carbonate of magnesia ...... .  . ..................   1.378
Alumina, iron, etc ................ ..o6o
Silicious residue.    . .        .......            . .     g8o
Total... .. .. .. .. . .. .. .. .. .. .. . .. .. .. ..     _88

  It will be seen that these samples do not even approach a
dolomite in composition, as the proportions of the carbonates
of lime and magnesia are not such as are required to form this
substance. This analysis cannot be used as a representative
one, as it is not made from an averaged collection of samples.
Nevertheless, it is undoubtedly true that the amount of mag-
nesia in the rock is quite small. It is, however, of compara-
tively little importance, except as a matter of scientific interest,
whether or not the rock is the equivalent of the Galena lime-
stone. It at least occupies the place in this lead region that
the Galena limestone holds in the lead district of Illinois,
whether that limestone has thinned out in this direction or
simply changed in its composition.
  The group of rocks in this region is made up of a series of
limestones and shales in the upper part, with a series of mas-
sive limestones at the base.
  The total visible thickness of the whole section is between
325 and 375 feet.
  The shales preponderate greatly towards the summit, the
limestone beds being thin and scarce. For this region the
group has been locally divided into the Ad Shale and Limestone"
division, which, without doubt, is part of the Cincinnati Group,
and the "Massive Limestone" division, which may, in part,
correspond to the Galena limestone.
  The thickness of the first named division is at least i6o
feet, and of the massive limestone about 125 feet, the base
of which is not visible. The accompanying plate represents
This is probably not the total thickness for the county; the upper series may be thicker
by 50 to 75 feet, possibly more, than was seen in the region under study.
254



TO

 



                  LEAD REGION OF HENRY COUNTY.                              1 I

sections made at and near Lockport, which may be taken to
represent typical ones of the entire region. It may include
certain rocks seen near Drennon Lick; but their place is
yet unsettled; and for all practical purposes it matters little
whether or not they are included.
  A detailed description of the strata making up the sections
is here given.
  Section I, made on the Franklin and Flat Creek road, de-
scending toward Lockport to Six Miles Creek.
x. Drab shale and limestone. The lime-tone is in beds of two to six inches in
    thickness, sparsely sc.ttered through the shale. The top beds abound in
    Strphmena aterata, Zigospira modesta (), and corals .5.0.. .  .  .   .  So feet.
2. Drab shale with a few limestone bcds. The limestone at the top is mostly
    drab, earthy, and somewhat sandy, and in thin layers. Laptaena sehea
    () and corals are found, the latter being quite abundant. This division
    differs principally from No. a in the great preponderance of the shale over
    the limestone. About the middle, for 3o feet, there is scarcely any lime-
    stone. Towards the base, however, the limestone increases, some of the
    beds measuring sil inches in thickness............... .                75
3. Drab shale and limestone. The limestone beds are coarse in texture and
    bluish grey usually, and are filled with Lrptaena serisca and Ortis em.a-
    cerata (). The downward limit of the Lepiae a is about five feet above
    the base of this division...... . . . . . . . . . . . . . . .   .     40
4. Limestone with some shale. Some of the limestone beds are 12 inches thick.
    Gasterupoda make their appearance in this division, and mark it as the
    "Gasteropod Beds ;" they are Cyvaeema bilax, Beleretphx bilebatus,
    Pleurotomaria lenticularis (), Murchisonia bicinta, etc., associated with
    Strophomena aiternata, Zigespira modesta, An-doxfepsu (), and an Orn'A-
      ras. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .     35
5. Nearly all limestone with some shale partings. Organic remains are mostly
    corals and Zigospira modesta..... . .. . . . . .  . . . .. .    .    30
6. Limestone abounding in Rhyn-eonAla s-apal, and containing great numbers
    of Z       -goesira modest. at the middle.  "Rhy.-onella capax bed " . .  . . . s o
7. Grey and bluish heavy-bedded limestone. Stro/mena alternata is abund-
    ant in most of the layers, and especially at the bottom. The rock also
    contains what appears to be a small specimen of Ortis subguadrala, and
    also one of Orthis lynxTo Six Miles Creek..... . . . . . .    . 85-go

    Another section was made on the Pleasureville road, on the
hill back of Lockport, which differs somewhat from the fore-
going in its upper members. It is No. 2, and as follows:
I. Reddish-brown shale, somewhat marly, with a few beds of drab sandy lime-
     stone scattered through it...... . . . .  . .. . . . .  . . ..   .    5 feet.
 2. Coarse, bluish-grey limestone and a little drab shale..... . . . . .   .   25  "

  The section representing the beds at the Silver and Spar mines should be opposite the
 lower part of the section No. z. Its position on the plate is due to a mistake.
                                                                             255

 




A RECONNOISSANCE REPORT ON THE



3. Shale and limestone.2.0............         .  .....   . . ..    .  20 feet.
4. Limestone and shale, mostly coarse limestone.                              5
5. Shale, with some limestone...                                       15
6. Shale, with a little limestone at the base .45
7. Shale and limestone, limestone predominating in the lower 5 feet .25
8. Shale and limestone. The limestone beds are usually drab colored, and
      sandy in composition. Some are blue at the interior but drab outside, and
      a few of the beds are dark grey in color and coarse-textured. These are so
      abundantly filled with Leptuana as to fit them to be called the "Leptaena
      beds...  . . . . . . . . . . . . . . . .. . . . . . .. . ...      35   I
 9. Coarse limestone and shale, mostly limestone abounding with purple shells of
      OMrtha emarata. . . . . . . . . . . . . . . . . . . . . . . . .       5
io. Limestone and shale..o 20
i. Nearly all limestone. About five feet of the upper part is made of shale. The
      gasteropod beds of section No. X are included in this number.           55
12. Limestone, the Rhyncondla avpax bed .2 "
13. Grey sparry limestone.4 .4
14. Grey limestone, containing much calcite, contains remains of .SfrpAom-na
      shells replaced by calcite; also corals, and fragments of Crinoid columns.
      Siroplwhoena a&ernata is quite abundant at about the middle of the bed . .  x5
i5. Hard, sparry limestone; color, bluish grey to light grey; lies in beds of from
      three inches to six inches or one foot in thickness, and is crossed by numer-
      ous seams of calcite. The rock is filled with Stropshwnena aternata, which
      was the only fossil found............           .......                  . .    3

   The lead deposits here are in numbers 14 and 15.
   On the Kentucky river, opposite "eLittle Mountain," near
Mr. Patterson's house, the following section was obtained.
The measurements were approximated:
i. Grey crystalline limestone, with aragonite filling the shrinkage cracks . . . . .  6 feet.
2. Blue limestone, containing gasteropods, several specimens of a Modiotepns, and a
     few trilobite plates... . . . . . .. . . . . . . . . .   . ... . . .   5
3. Ashy blue earthy limestone abounding in trilobites, and with aragonite filling the
     cracks and joint.                                                         5
4. Grey limestone, lumpy on the surface.      ............               . .  8

   Ambonychia      radiala, Strophomena         alternala, and     trilobites,
probably belonging to the genus Asaphus, were found in
addition to those fossils mentioned above.
  The rocks in this lead region are nearly horizontal, although
from Frankfort down the Kentucky river to a point below
the mouth of Drennon Creek there certainly is a fall of the
beds in a northwardly direction. At Frankfort a limestone is
exposed near the water's edge, which is below any in this
district.
256



12

 



LEAD REGION OF HE[NRY COUNTY.



                            III.
        SOME GENERAL NOTES ON MINERAL DEPOSITS.
  It is deemed advisable, for the benefit of those unfamiliar
with ore deposits, to give some notes on their various forms
before entering into the discussion of those in this region.
Among the classes of ore deposits are numbered veins, seg-
regations, impregnations, and ore beds.  The only form,
however, found in this district, so far as I am aware, is to be
classed among the veins.
Veins have been divided according to their texture, posi-
tion, and extent into-
    s. True veins;                4. Bedded veins;
    2. Gash veins;                5. Contact veins; and,
    3. Segregated veins;        6. Lenticular veins.
 Among these many modifications are found; and all authors
do not adopt precisely the same form of classification.
Lenticular veins may more properly be termed lenticular
vein-masses, as they are the fillings of cavities which, lenti-
form in shape, terminate in all directions-thinning out as it
were. They, however, often seem to be a local widening of
fissures of some considerable extent. They may be either
vertical or parallel with the stratification of the country rock;
or, in fact, they may have any direction.
  Contact veins are those inclosed between dissimilar forma-
tions, and separate the formations from each other.
Bedded veins traverse the country parallel to its stratifica-
tion, and are only distinguishable from beds by their occupy-
ing a fissure, having been introduced into the rock since it
was laid down, and not at the time of its deposition.
Segregated Veins or Segregated Deposits.-The latter term
is the more acceptable, as all the mineral deposits placed
under this heading do not have the character of veins.
Segregated deposits are those accumulations of minerals, or
ores brought together in cavities, limited in their extent on all
sides.



13



"IL ILK



2S7

 


A RECONNOISSANCE REPORT ON THE



  Sometimes these cavities have such forms that they resem-
ble veins; but as a rule they are the result of erosion, either
in the direct washing out, from the surface down, of cavities
in the rock, or by undermining, or a wearing away of the bed
in some other manner, and are not due to a fracturing of the
rock.  In size they vary from a few inches to many yards in
width, and are of all forms, from the vein-like to that of the
"cave" and "pot" deposits.
  In some instances this class of mineral deposits are doubt-
lessly due to replacement; but, usually, the matter is introduced
from above. It is probable that there are few such deposits
which have not been introduced from the exterior. Some seg-
regated deposits have distinct selvages, are frequently crys-
talline in texture, and, when vein-like in form, their character
is not always to be recognized at first view.
  The two following forms of veins are so well defined in
Whitney's "Metallic Wealth of the United States" that I
avail myself of his descriptions.           I
  Gash veins " hold an intermediate position between segre-
gated and true veins. Like the latter they occupy pre-existing
fissures; but these are of limited extent, and not connected
with any extensive movement of the rocky masses. They are
usually confined to a single member of the formation in which
they occur, terminating below, when a marked change in the
lithological or mineralogical character of the rock takes place.
  " Lateral branches will usually be found in connection with
the main fissures, which may or may not be nearly vertical,
according to circumstances; but whatever their position, the
two sets of cracks will be nearly at right angles with each
other, and will possess the same character in regard to their
mineral contents, although one set will generally predominate
over the other greatly in extent."
  As Professor Whitney states, this class of veins occupy
fissures that are never the direct result of "extensive move-
ments of the rocky masses." But that there are instances in
which the formation of the fissures have been, to a certain ex-
tent, influenced by such movements, is true beyond doubt.
S58



14

 


              LEAD REGION OF HENRY COUNTY.                15

  Gash veins are due to a shrinkage of the rock in which
they occur, and are, therefore, simply the filling matter of
shrinkage cracks brought about by various agencies.
  True veins are indefinitely deep fissures, which have, to
some certain extent, been filled with minerals or ores; "or,
in other words, an aggregation of mineral matter, accompa-
nied by metalliferous ores, within a crevice or fissure which
had its origin in some deep-seated cause, and may be pre-
sumed to extend for an indefinite distance downwards.
  -True veins are almost universally admitted by geologists
to have originated in ' faults' or dislocations caused by great
dynamical agencies connected with extensive movements of
the earth's crust, and for this reason they are believed to
extend indefinitely downwards, an assumption which is sup-
ported by facts, since no well-developed and defined vein has
ever been found entirely terminating ini depth.
   Gash veins, on the other hand, as before remarked, occu-
pying fissures which have resulted from shrinkage of the rock,
cannot be expected to extend into strata of different character
from that of the bed in which they originated.
   The linear extent of true veins is very various in different
instances.  Some of the longest known have been traced
many miles; but, usually, even if they extend for so consid-
erable a distance, they are not found to be impregnated with
ore through the whole of their course."

                            IV.
                CHARACTER OF THE DEPOSITS.
  So far as they have been explored, the lead deposits of
Henry county lie in approximately vertical fissures, which
occur in the - Massive Limestone" division of the Upper Cam-
brian rocks of this district. The lead, in the form of cubic
crystals of galena, sometimes accompanied by small quanti-
ties of zinc sulphide (the black blende), is held in a gangue
of dense baryta.  The metal is sprinkled, apparently indis-
criminately, through the baryta, and the quantity varies greatly
at different parts of the lode. The vein-stone is not always
                                                          259

 


A RECONNOISSANCE REPORT ON THE



wholly of baryta. In some instances it is a mixture of baryta
and caic. spar and some earthy, limy matter; and cases were
noticed where caic. spar, in the form of large crystals, formed
the larger portion of the vein.
  No instance was observed where a vein showed a distinct
selvage; the vein-stone was always found to completely fill
the fissure, lying in direct contact with the limestone walls.
  So far as my observations extend, there is always a set of
fissures traversing the rocks in a nearly due north and south
course. Extending from these are other cracks; but they are
quite variable in their direction and extent. They are found
coursing towards nearly every point of the compass, having,
however, a more decided bearing towards the southeast.
  The main fissures, however, do not extend in a decidedly
straight line by any means. They, in fact, make many turns,
proceeding in a series of offsets-in a zig-zag manner. This
feature in the fissures alone goes far towards determining
their origin and character.
  They show, undoubtedly, that the fissures are simply the
result of shrinkage cracks, such as exist in many limestones
similar in composition to these; and that they were chiefly
due to the same causes that produced other such cracks.
Originally they had, perhaps, little more length or breadth
than the lateral erevices now extending from the fissures.
  It is reasonably to be presumed that the beds; varying in
texture, shrank unequally, thus distributing the cracks some-
what irregularly and without connection with each other.
This is a feature not at all uncommon in limestones having
the composition of those in this region. It may, in fact, be
noticed in the rock bed of any stream in this district, and the
view presented there will give a very fair idea of the original
form of what are now the lead-bearing fissures.
  The widening of these shrinkage cracks, their connection
with each other, thus producing one continuous fissure, and
their northwardly course, is, in all probability, largely due to
one cause.
s60

 


LEAD REGION OF HENRY COUNTY.



  The key to the explanation is probably found in the course
of the great uplift of Upper Cambrian rocks, known as the
Cincinnati axis, in which the fissures occur.
  This uplift has a northwardly trend, and, according to Dr.
Newberry's views, the rocks seem to have been elevated quite
gradually. This elevatory process, although too slow to pro-
duce any great fractures, would certainly have a tendency to
disjoint the beds, and, the beds having already been fissured
to a certain extent, the pressure on them would find relief in
the widening and connecting together of those previously-
formed cracks, thus making the irregularly trending fissures
we now see. It is not improbable that the chemical changes
which were in force when the minerals now filling the fissures
were brought towards them, also bore a part in their forma-
tion; but it is probable that this was a subsequent, and, we
may say, locally modifying operation, the open spaces having
first existed as shrinkage cracks, towards which the minerals
were carried by their solvents.
  To put the explanation in simpler form, we have merely
to consider that the fissures are pt-imatily due to shrinkage
cracks (such as are common to nearly all limestones that
are at all earthy in their composition), and that the force
by which they were widened, and their form was, to a large
degree, caused by the uplift, the rocks being so broken by the
pressure as to connect the cracks, and the fissures thus caused
a decided course. The angles of the broken parts would soon
have been removed by friction.
  If this is accepted as a correct account of the origin of the
fissures, it is not difficult to understand why we find a promi-
nent set of fissures extending to the north and south, while
those to the east and west are of minor importance.
  The fact is not disregarded that in some of the lodes there
seem to be evidences of friction on the vein matter, striated
surfaces not being uncommon in it, as if th