xt77d7957f16 https://exploreuk.uky.edu/dips/xt77d7957f16/data/mets.xml Kentucky. State Geologist. 1889  books b97-21-37317666 English E.P. Johnson, Public Printer and Binder, : Frankfort, Ky. : Contact the Special Collections Research Center for information regarding rights and use of this collection. Mollusks, Fossil. Paleontology Silurian. Paleontology Devonian. Paleontology Kentucky.Nettelroth, Henry, 1835-1887. Kentucky fossil shells  : a monograph of the fossil shells of the Silurian and Devonian rocks of Kentucky / by Henry Nettelroth. text Kentucky fossil shells  : a monograph of the fossil shells of the Silurian and Devonian rocks of Kentucky / by Henry Nettelroth. 1889 2002 true xt77d7957f16 section xt77d7957f16 




KENTUCKY GEOLOGICAL SURVEY, J. R. PROCTER, DIRECTOR.



Kentucky Fossil Shells



      A MONOGRAPH OF THE FOSSIL SHELLS

                   OF THE



fillrian and Devonin Rooks of KeWtuoky



   BY HENRY NETTELROTH, C. E


                 1889.


           FRANKFORT, KENTUCKY
ELKCTROTYPED AND PRINTED BY E. POLK JOHNSON, PUBLIC PRINTER AND BINDER
                  1889.

 



































COPYRIGHTED BY KENTUCKY GEOLOGICAL SURVEY, 1880.

 

                    TABLE OF CONTENTS.




                                                               PAGE.
Letter from the Author-                                           3-4
A Short Sketch of Geology -5-V7
Description of Genera and Species-                             28-23(
Index to Genera and Species described -                       231- 239
Index to Species described -                                  240-245
Plates and Explanatory Text --                              I-XXXVI

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LETTER FROM THE AUTHOR



MR. JOHn R. PROCTER,
                Director Ketucky Geological Survey:
  DEAR SIR: The work of describing the fossil shells, or Mollusca, from the
Falls of the Ohio, which you kindly assigned to me some years ago, has,
unfortunately, been delayed by severe illness of several years' duration. It
was only during the past winter that I regained sufficient strength to complete
it. This monograph contains about two hundred and twenty species, forty-
three of which are new, and originally described by me. The descriptions
and illustrations of the balance are scattered over many different State
Reports, Monographs and Periodicals, accessible to only a few persons in
Kentucky, and, for this reason, it was necessary either to copy those figures
and descriptions, or to reproduce them from our own material. All of our
illustrations are original, with the exception of three or four, which are
copied from Prof. Hall's 27th Regents' Report. The drawing and engraving
was done by Mr. Chas. Starck, of the Louisville Lithographing Co., who
deserves great credit for the pains taken and the skill shown in the execution
of this work. Of the original descriptions of known species, I copied some
entirely. Coming, as they were, from the skillful pen of Prof. Hall, it was
impossible to improve them. Others I have remodeled, and some set aside
and replaced by new ones. In many cases, the descriptions were made from
single, not well preserved, specimens, which rarely showed the true characters
of the shells in their original condition, and, therefore, led to errors in the
descriptions. The large and excellent material now found in about a dozen
collections here in the Falls Cities, while enabling me to correct those mistakes,
has also compelled me to change descriptions coming from far superior palm-
ontologists. The larger number of our fossil shells were, heretofore, described
and figured by Prof. James Hall, of Albany, New York, in his numerous
reports and pamphlets, most all of which he presented to me, with the kind
permission to make the broadest use of his illustrations and descriptions. For
such exceptional generosity I can thank him only by this public acknowledg-
ment. The material used in the preparation of this monograph belongs partly
to my own cabinet, and partly to the collections of the following gentlemen:

 

LEITER FROM THE AUTHOR.



Major Wm. J. Davis, Profs. Wim. J. McConathy and J. T. Gaines and Dr.
James Knapp, of Louisville, Ky., Prof. A. C. Goodwin, of Charlestown, Messrs.
Orlando Hobbs, Henry Peters and Mr. Fogg, of Jeffersonville, Indiana. These
gentlemen have rendered me all the assistance I desired or needed, for which
I here express my thanks. To Major Wm. J. Davis, the author of " Ken-
tucky Fossil Corals," I am especially indebted for much valuable information
given me, while on our numerous collecting trips, and during the preparation
of this work. It has pained me to see the valuable collection of the late Dr.
James Knapp, from which Prof. Hall received most of his Ohio Falls speci-
mens, leave our State. Though in corals it was greatly inferior to the cabinet
of Major Wm. J. Davis, and in shells not equal to my own, it contained some
very rare specimens which it may be impossible to replace.
  Our shells have generally retained their original form, not having saffered
from compression or distortion, as is the case with so many fossils from other
localities, and their silicification has prevented all wear and rubbing after sepa-
ration from their matrix, while, on the other hand, their changing into horn-
stone has, in many instances, obliterated the original fine surface-markings, for
the study and description of which we have to acquire material from other
localities.
  The descriptions of fossils I have prefaced by a short article on geology and
paleontology in general, containing information indispensable to any one who
wishes to gain an understanding of the fossil remains of the fauna and flora
of former ages. In preparing said article, I have made extensive use of the
works of Dana, Lyell and others.
  Hoping that this monograph will meet with your approval, and that it may
be of service to the students of geology, in spite of its many shortcomings,
which, knowing your kind disposition, I feel assured you will overlook or
excuse, I express here to you, dear sir, my many thanks for your kind con-
sideration and indulgence, and remain
                  Very respectfully, your obedient servant,
                                                  HENRY NE'rTELBOTH.
  LOUISVILLE, 1887.



4

 








SHELLS



OF TUE



SILURIAN AND DEVONIAN ROCKS.

               BY

         HENRY NETTELROTH,



EPAR-'T I.



A SHORT SKETCH OF GEOLOGY.



FossilL

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                    A SKETCH OF GEOLOGY.



  The name "Geology" is derived from the Greek words "ge," the earth, and
"logos," a discourse, thus indicating a science of the earth, a science investi-
gating the different materials of which the earth is composed, and also the
manner in which these materials are arranged. Geology gives us, also, the
history of our planet from its beginning to the present time-examining all
the processes through which the earth has passed, from its original gaseous
condition until it acquired its present form and structure. It furthermore
enables us to obtain extensive and valuable information about the animal and
vegetable life which covered our globe during bygone ages.
  Geology is a science of comparatively recent date, though we find some geo-
logical knowledge among the ancient Romans and Greeks, and in the writings
of the middle age. All that knowledge, however, amounted only to a few
isolated speculations, nearly always based upon erroneous suppositions, and
never resulting in the establishment of a regular system. Geology as a science
was originated during the last century, but received its main development dur-
ing the present one. In spite of its short existence, it has outgrown many of
its sister sciences, and ranks to-day among the most important ones at the head
of the scale. Its founders and chief promoters are mainly found among the
English, German and French savants, and during the present cantury our own
country has contributed its full share to its advancement. The names of LyeJll
and Murchison, of Leopold von Buch and Goldfuss, of Cuvier and Verneuil,
and of our own eminent geologist, Professor James Hall, of Ner York, and
many others, will be known to the students of this noble science through-
out the coming ages.
  Geology has for its territory the whole earth, as far as the same is accessible
to its investigations. These are not confined to the surface, but penetrate as
deep into the interior as artificial excavations for mines and artesian wells
allow. Still greater and better opportunities than these artificial openings,
which are limited in numbers and dimensions, are offered the geologist, for his
researches, by the peculiar figuration of our planet's surface, where deep
valleys alternate with high mountains, and where the strata are bent to such a
degree that we find them at one place deep below the surface, whilst at a dis-
tance of a few miles the very same layers may be outcropping at the slope of
a hill, or may even form the surface rocks of extensive districts.

 

PALA:ONTOLOGY OF KENTUCKY.



  Vast as the geological field appears, and in reality is, it, nevertheless, forms
only a small portion of the whole contents of our globe. The deepest excava-
tions rarely extend to a depth of 2,000 feet below the level of the sea, though
their absolute depth may be greatly in excess of this, inasmuch as most of
them are in mountainous regions. The bending of the strata very often gives
us an insight into greater depths, but even this amounts only to a few miles,
and forms only a small portion of the earth's radius. Beyond these depths
geology is barred, as far as actual observations are concerned, but its inquiries
may penetrate deeper; it may speculate about the nature and condition of the
earth's interior. About this matter different theories have been advanced, but
as all of them are based on mere speculation, none have met with a general
acceptance by the scientific world. Whether the center of our globe is solid
or fluid, whether it is a vacuum or filled with compressed air, we are unable
to decide with certainty. Some facts speak for a solid and others for a fluid
center, and still others can not be accounted for by either condition.
  Some European scientists, like Leslie and Halley, consider the earth a hollow
sphere, which, according to Leslie, was filled with imponderable material, pos-
sessing an enormous repulsive force. These philosophic speculations of savants
were taken up by Captain Symmes, of Kentucky, who, by adding his own
fantastic dreams, enlarged them to the so-called " Symmes' Theory." Symmes
insists that the interior of our globe is not only hollow, but that it is also
inhabited by animals and plants; that it possesses a very mild climate, and is
illuminated by two planets, which he calls Pluto and Proserpina. He felt
so convinced of the existence of his subterranean country, that he repeat-
edly extended private and public invitations to Alexander von Humboldt, Sir
Humphrey Davy, and other celebrated scientists of this country, and of the
old wvcrrl, to accompany him on his intended subterranean expedition.

                                 ROCKS.
  The solid portion of the earth is composed of different materials or rocks.
The term "rock," as commonly understood, signifies a hard and stony mass,
such as granite, quartz or limestone, but in its geological meaning, it embraces
all solid constituents of our globe, the hard and stony, as well as the soft and
incoherent matter; thus, loose sand and soft clay are just as well included in
that term as basalt and quarrystone. Before geology enlightened the people,
it was the general belief that all the rocks, with their present form and arrange-
ment, were thus created. This belief, though still adhered to by the ignorant
masses, and by bigots, has disappeared from the minds of all who ever came
under the influence of geological reasoning. Geology informs us, that all the
rocks in their present structure, composition and arrangement, are the pro-
ducts and results of many different conditions under which our earth existed,



6

 

A SKETCH OF GEOLOGY.



and of many different processes through which it has passed during the many
ages of its existence. By whatever influences the rocks may have received
their present characters, they received their original form and structure by the
agency of fire. All the rocks, without exception, passed, in the beginning,
through a molten condition, out of which, by subsequent cooling, they re-
ceived their first form as solids.  But in the course of time another agent
appeared and changed many of the existing forms. Water, the powerful
opponent of fire, went into action, and by its chemical, as well as mechanical
influence, dissolved a large portion of the fire-produced formations, and carried
them to distant localities, where, under favorable conditions. they were de-
posited as sediments, forming those rocks which are mainly characterized by
their arrangement into strata or layers.  Again, we find many of these sedi-
ment-formations have been subjected to the influence of heat, by which they
lost some of their former characteristics. Their crystallization, and the total
absence of organic remains, prove the action of heat, while, on the other
hand, their stratification, which is generally retained, testifies to their sedi-
mentary origin. Thus we will notice a natural division of all the rocks into
the following three classes:
  1. Rocks originally formed by fire and not afterwards changed, the igneous
rocks.
  2. Rocks formed in water by sediments, the stratified or sedimentary
rocks.
  3. Rocks originally formed as sedimentary deposits, but afterwards changed
by heat, without losing their stratification, called metamorphic rocks.
  The igneous rocks are generally subdivided into volcanic and platonic rocks.
Their difference is caused by the condition under which the cooling of the
molten masses took place. In the volcanic rocks, the molten matter appeared
either on the surface of the earth, or at least very near to the same, where the
cooling was rapid, and where the forming rocks were not subjected to the
heavy pressure of the superimposed strata.
  The platonic rocks resulted from greatly different conditions. Here the
molten masses did not penetrate the surface strata, but remained deep in the
interior of the earth, or at least at the bottom of deep oceans, where the cool-
ing process was retarded, and where the new formations were compressed by
the weight of the overlying layers.
  In the column of strata we generally find the plutonic rock at the bottom.
Next above come the metamorphic formations, which are superimposed by
the sedimentary and volcanic rocks. This arrangement led the earlier geolo.
gists to the belief that the plutonic and metamorphic rocks were older than the
others, consequently, they called the lower primary formations, and the upper
the secondary formations. The older school of geologists adhered to the



7

 

8



PALEONTOLOGY OF KENTUCKY.



so-called neptunian theory, according to which all the rocks, with the only
exception of the volcanic lava formations, were considered as produced by
water, or to be of aqueous origin. If this theory had proved correct, the views
of the old school about the comparative age of the different rocks would be
sustained. But progress in geological science has upset the neptunian theory,
and established in its place the plutonic theory, which makes fire or subter-
ranean heat the main agency in the production of the plutonic and met-
amorphic rocks.
  This new theory does not admit the classification of primary and secondary
rocks. The first rocks ever produced, which formed the first thin crust of our
globe, were dissolved by. water and removed to other localities, where they
furnished the constituents of the sedimentary formations.   Even a large
portion of these have been ground up by weather and water, to provide the
material for later deposits. Rocks of all the different classes have been formed.
during the past, simultaneously, and may be in process of formation at
the present time. The terms primary and secondary are, therefore, obsolete,
inasmuch as they indicate the comparative age of the different rocks.

         SEDENTARY OR STRATIFIED ROCKS.
 Though all the different classes of rocks are of great interest to the geologist,
 still the most important of all is that including the sedimentary formations.
 The rocks of this class are always arranged in layers or strata, and they are,
therefore, generally referred to as stratified rocks. They are of greater impor-
tance to the geologist than the other formations, because they furnish him the
main material for his investigations. Most, if not all, of them have been
formed since the beginning of organic life on our planet, as proved by the
remains or traces of animal and vegetable organism preserved in their strata.
  The most important among the different points which the geologist has to
consider in regard to the sedimentary rocks, are: their mineral composition,
their arrangement in strata, their relative age, and, most of all, their organic
remains.
  In regard to their mineral composition, we may divide them into three
groups, the siliceous, or arenaceous rocks; the clayey, or argillaceous rocks;
and the calcareous rocks, or limestone.  The main constituent of the first
group is silica, in the form of quartz-grains or sand; that of the second group
is clay, a mixture of siliceous matter, with a large amount of alumina and
oxide of iron, and that of the third group is carbonate of lime. It is impos-
sible to separate these three groups by a well defined division line. Some
rocks form a kind of connecting link between the first and second, and others
between the second and third group, while again, others may combine the
siliceous and calcareous rocks. The first group is represented by sandstone,

 

A SKETCH OF GEOLOGY.



the second by shale, and the third by limestone. Argillaceous rocks are
easily identified by the peculiar earthy odor which they emit when breathed
upon, while the limestones may be detected by the aid of muriatic acid, which
causes effervescing when applied to them. Upon sandstone acids have no
effect whatever.
  STRATIFICATION.-Stratification is the arrangement of rocks into different
layers or beds. It is a characteristic feature of all the sedimentary forma-
tions. Stratification can only be produced by sedimentation, and the latter
can, as far as geological strata are concerned, only take place in water charged
with solid or earthy matter, which is kept in suspense in the shape of mud.
Solid material has generally a greater density, or specific gravity, than water,
and, therefore, can be kept in suspense by the latter only so long as the lateral
motion of the water overcomes the action of gravitation. As soon as the
water ceases to move, the mud falls to the bottom, where it forms the sediment
which afterwards, under the enormous pressure of superimposed masses,
transforms into solid rock. If such sediment formation had gone on continu-
ously, and always under exactly the same conditions, throughout a whole
geological period, all the rocks of that formation would form a solid, un-
broken mass. But the sediment formation suffered frequent interruptions,
extending over shorter or longer periods, and was subjected to many changes
in its material. These circumstances caused a differentiation in the deposits.
Any interruption of the formation, or any change in the material, were indi-
cated by lines or planes of separation, while the different layers, thus produced,
were distinguished by color and texture.
  The solid or earthy materials with which the waters are charged, are derived
partly from the dry land by the influence of heat, frost and rain, and partly
by the never-resting waves of the oceans grinding up the cliffs and beaches of
the seashores. These agencies are employed to reduce the elevations of the
dry lands to the level of the oceans, and, if they were not counteracted by
other forces, would accomplish their task in less than six millions of years.
It is estimated that the average elevation of all the continents and islands does
not amount to fully one thousand feet; and, on the other hand, the work
accomplished by denudation is computed to be one foot in six thousand years,
extending over the whole area elevated above the ocean. Such calculations
are only mere approximations, based upon conditions which may change
considerably in the course of time, and should never be used for framing
deductions, without making great allowances. That the work of denudation
must have been different during the different ages of the past, can not be
doubted. There were periods when a very high temperature prevailed all
over the earth, from the poles to the equator, causing a heavy rainfall, and
lending the water a greater dissolving power, circumstances which must have
    GUOL. Bux-2



9

 

PALACONTOIOGY OF KENTUCKY.



produced greater denudation. Then, again, other periods set in, when the
temperature of our globe was very low, when the excessive heat of former
ages was replaced by excessive cold. Frost is a very powerful agent in the
destruction of rocks. The hardest material which admits water into its pores
will be crumbled to dust by this destructive force. Here, again, denudation
must have been very large. Between these extremes in temperature, our planet
experienced some moderate climate which had not such a destructive influence
upon the solid material of our earth's crust.
  STRATA AND LAYERS.-These two terms are generally used as synonymous,
but some geologists make a distinction between them. They use the term
layer for each single member of stratified rock, and apply the term strata to
beds of the same material. Thus, if a section shows in its lower half limestone,
and in its upper half sandstone, it contains only two strata. though it may
show a great many layers.
  Layers and strata vary in thickness from an inch, and less, to many feet.
Very thin layers are called laminu, and for thin strata, the term seams is used.
If all the strata had remained undisturbed in their original position, all would
be nearly horizontal, and parallel to each other; but the many upheavals and
depressions to which our earth's crust has been subjected, have disturbed their
original horizontal and parallel arrangement, and we now find them occupying
every imaginable position in relation to each other. Wherever two sets of
strata or layers are nearly parallel to each other, it proves that the older set
was not disturbed in its original position before the younger or later one was
deposited upon it; but whenever the upper strata rests on the edges of those
below, these latter have been disturbed before the formation of the upper
ones took place. In the first case, where the parallelism of the strata is main-
tained, they are said to be conformable; but whenever the planes of the upper
layers rest on the edges of the lower ones, they are called unconformable.
Conformability of strata indicates a period of rest, whilst unconformability is
a certain proof of disturbance. Any movement in the earth's crust must pro-
duce some changes in its layers or strata, resulting either in a bending or
breaking of the same, whereby fissures, folds and faults are originated. Fis-
sures are rents caused by breakage, without any displacement of the rock on
either side of the fracture, below or above their former level; but, whenever
the masses on one side or the other have changed their positions, either by
elevation or depression, the rent becomes a fault. According to the great
difference in the magnitude of the forces producing the faults, the size of the
latter must also differ greatly. We find them measuring from an inch and
less, to many hundred feet. Faults are of great inconvenience to miners,
especially where they appear of considerable size. Folds of strata are the
result of their bending without breaking; they differ in size from a few feed



10

 

A SKETCH OF GEOLOGY.



to many miles, and form, very often, extensive valleys and mountains. Strata
are very seldom found perfectly horizontal; they may be so for a short distance,
but, extending over a larger area, they will always show a certain amount of
curvature. These curves bending inward-that is, with their convexity toward
the center of earth-are forming troughs; bending outward, they form arches.
A line running, in a series of strata, through the highest point of their arches,
is called their anticlinal axis, and the line running through the lowest point of
their troughs is known as their synclinal axis. If no denudation had inter-
fered, we would always find the anticlinal axis to correspond with elevations,
and the synclinal with valleys; but, since, by the influence of weather and
water the figuration of our earth's surface has greatly changed, we often meet
with anticlinal valleys and synclinal hills. The correct location of these lines
is often of great importance to the geologist in surveying a certain district or
country, which he can easily accomplish if he bears in mind that his proceed-
ing from older upon younger strata leads him towards the synclinal; and nice
verna, if he proceeds from younger upon older formation he approaches an
anticlinal.
  'Two other important features of the stratified rocks are their dip and strike.
Upon these, to a great extent, depends the peculiar topography of the earth's
surface.
  Dip is the amount of the deflection of strata from the horizontal or level
line; it is measured by, or expressed in, degrees. If a layer has a dip of forty-
five degrees, it is bent downward, and forms with the horizontal surface an
angle of forty-five degrees. Wherever the dip increases to an angle of ninety
degrees, the strata stand on their edges in a vertical position. Strike is the
horizontal line drawn at right-angles to the direction of the dip. Rocks with
a southern or northern dip, will have an eastern or western strike. As long
as the dip of certain strata runs in the same direction, their strike is indicated
by a straight line; but as soon as the dip changes its direction, the strike will
assume the shape of either a broken or curved line. Rocks with great dip
produce a broken undulating country, and in accordance with the curved or
straight lines of the strike, we find the hills and valleys respectively winding
or rectilineal.
                          PALAIONTOLOGY.
  Palieontology treats of the animals and plants which inhabited our planet
during former periods, and may, therefore, be properly styled the natural
history of by-gone ages. From zoology and botany, it differs only in so far
as its objects belong mostly to an extinct fauna and flora, the remains or
traces of which are imbedded in the rocks and soils of the earth's crust. Palae-
ontology forms a science of itself; but on account of its intimate connection
with geology, it is generally considered as only a branch of the latter. The



t1

 

PALA&ONTOLOGY OF KENTUCKY.



objects with which paleontology deals are known under the name of " fossils,"
a term designating bodies "dug out of the ground," and which was formerly
applied to metals and rocks, as well as to organic remains. At present the
word fossil is used in a more restricted sense, applying only to such geological
objects from which science may deduce information about the organic life of
the past. These objects mainly consist In remains of animals and plants, such
as shells, teeth and bones; or stems, leaves and fruits; but they also include
the burrows and tracks of annelids, the footprints of saurians and other ani-
mals, and even the droppings of fishes and reptiles, which are known under
the name of coprolites. Some geologists class among the fossils even objects
produced by man, such as arrow-heads, spear-heads and canoes found in the
gravel and clay beds of our fields and river shores; but, inasmuch as they
properly belong to archaeology, they can not be counted among the fossils.
  The real nature of fossils was known more than five hundred years before
the Christian era, by Xenophanes. He observed the fossil remains in the
quarries of Syracuse, consisting of marine shells and fish-bones. He recognized
them as the remains of real animals, that had lived there at the bottom of
the sea, where they were imbedded in mud, which afterwards hardened into
the rocks then inclosing them. He also laid down the general proposition, that
the geographical features of our earth are not constant, but that, where land
now is, sea has been, and where sea now is, land has been. Afterwards this
clear conception of the real nature of fossils appears to have been lost, until
the end of the seventeenth century, when Nicholas Steno, Professor of anat-
omy in Florence, though a Dane by birth, gave them again a correct explan-
ation, and revived the theory of Xenophanes.
  Before Steno, during the fourteenth, fifteenth, sixteenth and seventeenth
centuries, fossils were regarded as mere figured stones, portions of mineral
matter which have assumed the forms of leaves and shells and bones, just as
those portions of mineral matter which we call crystals, take on the form of
regular geometrical bodies. Others considered them the products of the germs
of animals and of the seeds of plants, which have, as it were, lost their way,
in the bowels of the earth, and achieved only an imperfect and abortive devel-
opment. These opinions appear to as ridiculous, and we are inclined to sneer
at our ancestors for entertaining such ideas about a matter which is now so
clear and simple. People who believed in spontaneous generation, could have
no difficulty in taking fossils for sports of nature, and we know that spon-
taneous generation was generally believed in up to the present century; and,
even to-day, thousands of people, laying claim to a fair education, still adhere
to that belief These erroneous ideas about the nature of fossils were, long
after Steno's correct interpretation, maintained among common people, but
men of science became more and more convinced of the correctness of



12

 

A SKETCH OF GEOLOGY.



Xenophanes' theory. To-day, every person who has gained an insight into
paleeontology, knows that the fossils found in most of the sedimentary rocks
are originated by animal or vegetable remains, which became imbedded in the
mud at the bottom of the sea, during former ages. In speaking of fossils, we
generally describe them as remains of animals and of plants, which is not
in accordance with the facts, at least not for the majority of them, inasmuch
as, in the larger number, not a particle of organic matter is preserved, and
only the form of the imbedded body retained. The original animal or vege-
table substances dissolved and became replaced by calcareous, siliceous and
other minerals. The remains, therefore, underwent an active transformation
into stone, or became, as we call it, petrified. Fossils thus transformed ow
changed, are classed together under the name of petrifactions.
  This term is very often used as a synonym for fossils, but erroneously;
because not every fossil has passed through a petrifying process, while there are
many belonging to younger formations, that have, outside of form and struc-
ture, retained also the color and organic matter of the original remains. Every
petrifaction is a fossil, but not every fossil is a petrifaction. The process by
which the transformation of organic remains into mineral bodies is produced,
is of a chemical nature, and depends upon conditions not yet fully under-
stood.
  We must distinguish between petrifactions and incrustations, although the
latter are often classed among the former. Incrustations are generally pro-
duced in springs, whose waters are charged with a considerable amount of
calcareous matter, which settles upon immersed bodies, like flowers and
branches, or shells and bones, inclosing them with a mineral coat or crust,
but never permeating them, as is done in the case of petrifaction. By break-
ing such incrustations we find, either the inclosed bodies unchanged, or, if
they have disappeared, the place formerly occupied by them a hollow mould.
  Another transformation of animal matter is by many erroneously classed
among petrifactions. We sometimes notice in public papers reports of oases
where human bodies, resurrected after some years of interment, have been
found, not only well preserved in form, but so hard and stiff, and so much
increased in weight, as to appe