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Lincoln Phelps.

Lectures to young ladies, comprising outlines and applications of the different branches of female education, for the use of female schools, and private libraries online

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Inflammable Substances.

Sulphur is found in large masses, combined with oxy-
gen, forming sulphuric acid ; it unites with lime, and forms
gypsum, or plaster of Paris.

Carbon, or Charcoal, is a constituent of many slate
rocks, giving them a dark color ; it is the principal con-
stituent of that kind of coal which is found in beds. Car-
bon combined with oxygen, forming carbonic acid, is
combined with all limestone rocks.

Alkalies.

Potash and Soda. These alkalies do not exist in rocks
to a great degree, but soda forms an important constituent
of the water of the ocean and rock salts.

Besides the elementary substances above enumerated,
we will mention muriatic acid, which, combined with
soda, forms salt ; and phosphoric acid, which, combined
with lime, is a principal constituent of animal bones; the
latter acid is found in some limestone beds, but rarely
occurs in the mineral kingdom.

The few elementary substances which we have now
described, form, either separately, or combined, all the
simple minerals which compose rocks.

You will find it difficult, without some knowledge of
chemistry, to understand in what manner these elemen-
tary substances combine with others, forming a great



222 GEOLOGY.

variety of minerals, or rather you may be surprised that
when closely combined, they can be separated from the
materials with which they are united. The examination
of the elementary bodies, Earths, Metals, Inflammable
Principles, and Alkalies, properly belongs to the depart-
ment of Chemistry ; and the study of simple minerals,
belongs to the science of Mineralogy.

It is difficult to procure pure specimens of all the ele-
mentary principles, but the simple minerals are very
common, and should be procured in the commencement
of geological studies. The most important simple mine-
rals, which enter into the formation of rocks, are as fol-
lows :

Quartz. Hornblende.

Felspar. Limestone.

Mica. Gypsum.

Talc. Slate, or Argillite.

Chlorite.

These minerals are termed the alphabet of geology,
and you could no more learn to read words, without a
knowledge of the letters which form them, than you could
learn to distinguish the different rocks, without a knowl-
edge of the simple minerals of which they are composed,
We will now examine the most striking characteristics of
these minerals.

1. Quartz. This is the hardest mineral of which rocks
are composed ; it strikes fire when struck with steel ; it
is commonly white, though sometimes red, brown, or yel-
lowish, and sometimes transparent. It is composed of
silex, with a small portion of alumine. It is infusible, or
cannot be melted when unmixed ; but with soda or any
other alkali, it melts easily and forms glass. Quartz ex-
ists in veins, and sometimes in large beds ; even whole
mountains are found composed of this mineral, in grains
united without any cement, called granular quartz.
Combined with alumine and iron, quartz forms jasper.

2. Felspar is less hard than quartz, is more brittle,
and possesses a shining lustre. It is of various colors,
white, yellowish, green, and flesh-colored. Felspar con-
tains more of alumine and less of silex than quartz, with
13 parts in a hundred, of potash.



GEOLOGY. 223

3. Mica consists of very thin glittering leaves, (lamina)
which may be easily separated with a knife. Mica is of
different colors, white, black, and sometimes yellow, like
gold ; for which it has been mistaken by those who only
judge of minerals by a superficial observation.

4. Talc. This is similar in many respects to mica; the
plates are not like mica, elastic ; it is usually of a green
color, sometimes of a silvery white ; it feels smooth like
soap, to the touch.

5. Chlorite, (derived from a Greek word, cJiloros, sig-
nifying green) is of a green color, and often passes by
insensible gradations into talc ; it contains less of silex
than is found in either mica or talc, but more of magne-
sia and the oxide of iron, to which its owes its color.

6. Hornblende is of a blackish, or dark green color,
heavier than quartz or felspar, but not so hard, when
scratched with a sharp pointed instrument ; the streak is
a light green ; this mineral is sometimes found in large
masses, forming entire mountains, but more frequently it
is found as a part of compound rocks, called trap rocks,
the origin of which has, among geologists, given rise to
various opinions. Hornblende contains more of the
oxide of iron, than any of the simple minerals; for this
reason, it is more deeply colored.

A very common mineral called serpentine, from its spot-
ted color, resembling the serpent's skin, is formed by a
combination of hornblende with talc, or chlorite, often
passing by insensible gradations into one or the other of
these minerals.

7. Limestone, or Carbonate of Lime, when pure, is
composed of lime and carbonic acid, in the proportions
of fifty-seven parts lime, and forty-three carbonic acid; but
the limestone is often combined with magnesia, alumine,
silex, or iron. All limestones may be scraped with a
knife; they effervesce when acids are applied to their
surface : this latter property is an important test of the
presence of lime in rocks. There are a great many varie-
ties of limestone rocks, from the hardest marble to chalk.
Gypsum, or sulphate of lime, is of a whitish color ; it is
much softer than carbonate of lime ; it is found in beds,
but not constituting rocks and mountains, like limestone.



224 GEOLOGY.

It is, as its chemical name, sulphate of lime, would de-
note, a compound of lime and sulphuric acid. It is also
called plaster-stone, and, from the pi ace where it was first
discovered, plaster of Paris.

8 Slate, or Argillite, (in German called schistus) is
of a bluish or gray color, with a silky lustre ; the struc-
ture is such, that in general it admits of being split into
thin plates, as in the slate which is used for the roofs of
houses, and in writing slates. By being united with a
greater portion of carbon, it passes into a soft, dark, slaty
bed, called shale.

We have now enumerated the elementary principles
which enter into the composition of minerals, and con-
sidered the simple minerals, which, either separately
or combined, form rocks and mountains. In order
to know minerals, specimens must be examined, and
carefully compared with descriptions ; so that you can,
without any difficulty, distinguish a piece of quartz, or
mica, or any of the other simple minerals, and can also
recognize them when you find them in a state of combi-
nation with others. This then will be the first stage in
your geological study to know the elementary principles,
and the simple minerals ; and to procure specimens of
the latter, your first step towards collecting a geological
cabinet. You will of course understand, that each speci-
men is to be labelled and arranged in the order in which
these have been described.

We will now explain to you, how the simple minerals
just examined are combined to form the compounds
which constitute rocks and mountains. You must, howev-
er, recollect that in many cases, these simple minerals
themselves are found in large masses ; rocks and even
mountains of quartz are known to exist ; limestone under
various forms, often that of pure carbonate, is said to
constitute about one-eighth of the known substance of
the earth. Slate, or argillite, in nearly a simple state,
forms rocks and mountains ; but there are compound
rocks to be considered, which in the structure of the
earth are of far greater importance than the simple
minerals.



GEOLOGY. 225

Compound RocJcs.

Granite. Here is a piece of a rock, called granite;
you will perceive three distinct substances, which you
will recognize to be quartz, mica, and felspar: the
quartz is white, and has a crystalline appearance ; it
seems to consist of irregular grains, or, according to the
geological term, it is granular .* The mica is distin-
guished by its shining black scales, which you can easily
divide by the point of a penknife. The felspar is here
flesh-colored ; it seems to consist of finer particles than
the quartz, resembling the rough edge of procelain
ware.

You must not, however, expect to find exactly the
same appearances in every specimen of granite ; some-
times the quartz is gray, or smoky, the mica varying in
color through various gradations, from a silvery white to
black, and the felspar is often of a snowy whiteness.
Granite also varies in its constituent parts. We some-
times find talc in the place of mica, forming Talcy
granite, chlorite forming Chloride Granite, and horn-
blend, forming Sienite.}

Gneiss. This name was given to the rock we are now
to examine, by German miners ; it resembles granite, in
being composed of the same materials, but with less
felspar and quartz, and these in grains finer and less
distinct than in granite. The mica is often arranged
in thin leaves, J or layers ; the perfect gneiss rocks may
be split in the direction of the leaves of mica.

Although between a perfect specimen of gneiss and
one of granite, we might perceive a marked difference,
yet when the granite appears in fine grains with more
of mica and less of felspar, it passes into gneiss, and it
is by no means easy to ascertain the exact point where
the one passes into the other.

Mica Slate is composed chiefly of quartz and mica,
the latter being most abundant, often reflecting the rays

* This is said to have given rise to the name Granite.

t So named from Sienna, in Egypt, where this rock was an-
ciently used for monuments.

t This kind of structure is called foliated, from the Latin word
folium, a leaf.



226 GEOLOGY.

of light with much brilliancy. This rock is more slaty
than gneiss : the layers of mica are sometimes contorted
or bent out of a straight course. Mica slate sometimes
varies into gneiss and granite, though in its perfect state
its character may be easily recognized.

The three rocks which we have now examined, viz.
granite, geniss, and mica slate, are, as you see, all com-
posed of similar ingredients, but in different proportions
and differently arranged ; they form a great portion of
the principal mountain ranges upon the face of the
globe.

Having now instructed you in such preliminary know-
ledge as seemed necessary to enable you to comprehend
the general principles of the science, I shall now offer
the following outline of geology.

Geology is the science which exhibits the structure of
the globe, and the materials of which it is composed, as
far as they have been revealed to human observation.
It is supposed by most geologists that the materials of
the earth were once in a fluid state, and that the heaviest
minerals took the lowest place. It appears evident that
the earth very gradually became fitted for the habitation
of men and animals. The six days of the Creation,
spoken of in the first of Genesis, are supposed to have
been six periods of time, of a length which must have
comprehended many ages. That the day spoken of in
Scripture was neither a period of twentyrfour hours or
from sun-rise to sun-set, is manifest not only from geo-
logical observation, but from the language of the bible.
After enumerating the various days or periods of the
creation, the sacred historian speaking of them all under
one general head says, ' In the day in which God made
the world,' &/c. It is also said in scripture that ' with
the Lord a thousand years are as one day, and one day
as a thousand years/

Without attempting to go minutely into the subject of
the earth's formation as explained and taught by mod-
ern geology, I shall merely notice a few of its most
prominent facts and principles.



GEOLOGY. 227

It is found to be a fact that there is a class of rocks,
the materials of which are heavier and more compact
than any other, and which never contain any remains
of animals or vegetables ; they evidently appear to have
lain below all the rock formations which have been dis-
covered. These are called primitive rocks, being, as
it is supposed, the first formed* They are the follow-
ing:

First Class of Rocks.

Granite, Granular Quartz,

Gneiss, Granular Lime Rock,

Mica Slate, Sparry Lime Rock,

Hornblende Rock, Primitive Argillite.
Talcose Rock,

Granite, as has been remarked, is composed of quartz,
felspar, and mica ; it is found in vast quantities in many
countries ; it constitutes a large portion of many of the
highest mountains ; it forms a siliceous soil, not favor-
able to vegetation, and makes a beautiful and durable
building stone.

Genciss. This rock is composed of the same mate-
rials as granite, viz. quartz, felspar, and mica ; but the
mica is arranged in parallel layers.

Mica Slate is composed chiefly of quartz and mica;
the mica usually predominates. It disintegrates more
rapidly than granite or gneiss.

Hornblende Rock consists of hornblende and felspar;
when the felspar is in disseminated masses, it is called
Sienite. The predominant color of the rock is green,
sometimes inclining to brown. The sienite variety is
susceptible of a high polish, and forms beautiful pieces
for ornaments.

Talcose ROCK, is an aggregate of talc and fine grains
of quartz, and generally some mica. It is a slaty rock,
and of a silver-gray color.

Granular Quartz is made up of grains of quartz,
without any appearance of cement : when white, its sand
is used in making glass.

Granular Lime Rock is made up of grains hav-
ing a crystalline appearance : it receives a high polish,



228 GEOLOGY.

and is much used for monuments, pillars, and in build-
ing.

Sparry Lime Rock is made up of fine grains of car-
bonate of lime : it resembles Nova Scotia plaster. From
this stratum, nitrogen gas, in vast quantities, is supposed
to issue.

Primitive Argillite is a homogeneous rock, of a slaty
structure. It is used for roofing buildings.

A long period must have been required to bring the
materials of these primitive rocks into the compact and
hardened state in which we now find them ; for although
the Deity could, in an instant, have changed the most
subtle gasses into rocks and stones, we have no reason
to believe that he did not operate by second causes as
much in the formation of the World as he has since done.
Chemical and mechanical agencies undoubtedly were
brought into action to produce the intended effects: the
dry land at length appeared, the waters being gathered 1
together into oceans, seas, lakes and rivers.

After the first crust was formed around the earth, it
is supposed that some great convulsion in the interior,
either by means of volcanic fires, or the sudden percus-
sion of internal gasses producing earthquakes, burst
asunder this outer coat, and shattered into fragments, or
broke into larger masses, the rocks of which it was com-
posed.

At the breaking up of the rocky pavement of the
globe, and crumbling of primitive rocks, of which this
pavement was composed, a new formation was made of the
fragments of the other rocks, united together by a kind
of cement. This induces the opinion that volcanic fires
were agents in producing the great commotion which
tore up the foundations of the earth. Fire would of
course melt or fuse, in a degree sufficient to form the
cement ; for instance, where granite was thrown by the
side of limestone, the silex of the one in contact with the
alkali of the other would form a substance like glass,
which you know is produced by the melting of sand and
alkali together.

This second class of rocks are called transition
rocks, because they are supposed to have been formed



GEOLOGY. 229

at the changing or transition of the world from an unin-
habited to a habitable state.

The rocks belonging to this class are,

Transition Argillite, Graywacke, and

Calciferous Sand Rock, Old Red Sand Stone.
Metalliferous Lime Rock,

Transition Argillite is a soft, homogeneous rock,
mostly of a bluish or dark color. It composes the rocks
of the Cohoes Falls.* There seems to be very little dif-
ference between this and the Primitive Argillite, and it
is thought proper, by some geologists, to include them
all in one class.

Calciferous Sand Rock is composed of grains of quartz
and carbonate of lime.

Metalliferous Lime Rock is of a gray or slate color.
It derives its name from being often found to contain
silver and other metals.

Graywacke is an aggregate of sand cemented by clay ;
it often contains scales of talc and mica. The color is
usually gray. This rock constitutes most of the Cat-
skill and Alleghany Mountains.

Old Red Sand Stone is an aggregate of angular
grains of quartzose sand, held together by a ferrugin-
eous argillaceous cement. It forms a loose, red soil : it
is valuable for building : when wrought, it is called Free
Stone. It forms the bank of Connecticut River.

In the transition formation, we find the fossil remains
of plants and animals; the plants are all of that kind,
called in Botany stiped, that is, having no real stem, but
a frond like the ferns and palms. These plants differ in
several particulars from those which have the true stem
or caulis, and are therefore called cauline plants. The
seeds of stiped plants never have two cotyledons ; the
stalks grow from the centre outwardly, and are therefore
called endogenous^ while the stems of cauline plants
grow on the outside, and are called exogenous.

The fossil animals found in transition rocks are of

* These falls are on the Mohawk, a little above its mouth.

t The two words, endogenous and exogenous, are derived from
the Greek : the first signifies to grow internally, the other to grow
externally.

20



230 GEOLOGY.

races now extinct. At this second period of the world, a
strange and appalling state of things existed ; lizard-
shape animals, extending to monstrous dimensions; the
mastodum and megatherium of enormous bulk, and vari-
ous other huge and singular animals had possession of
the earth, and rolled their vast magnitudes over ferns and
palms of a size corresponding to their own.

In the meantime a new set of rocks were gradually
formed from the ruins of both primitive and transition;
these were called secondary rocks : other plants and ani-
mals were at this period created.

These rocks are,

Mill-stone Grit, Calciferous Slate,

Saliferous Rock, Geodiferous Lime Rock,

Gray Band, Cornitiferous Lime Rock, and

Ferriferous Slate, Pyritiferous Rock.
Ferriferous Sand Rock,

Mill-stone Grit is a coarse, harsh aggregate of sand
and pebbles ; the color is gray or reddish. It is used for
mill-stones.

Saliferous Rock constitutes the floor of all the salt
springs in the western country. It is used as a building
stone.

Gray Band is a hard fine-grained gray rock, so com-
pact that it may be considered homogeneous.

Ferriferous Slate is a hard silicious rock, lying over
iron ore. It often appears in the bed of the Western
Canal.

Calciferous Slate. This rock often contains carbonate
of lime; it embraces beds of plaster and shell limestone;
it forms, by disintegration, the best of soils.

Geodiferous Lime Rock. This name is given on ac-
count of small cavities which it contains, called geodcs.
This rock is found at Lockport and Niagara Falls.

Cornitiferous Lime Rock is made up of layers of shell-
limestone, containing beds of horn-stone: from this cir-
cumstance, it receives its name the Latin word cornus,
signifying a horn. This rock is remarkable for its numer-
ous caverns.

Pyritiferous Rock is a calcareous gray rock, abound-
ing in iron pyrites.

At length, the earth being made habitable, man is
formed ; after a series of ages, the fountains of the deep



GEOLOGY. 231

are broken up; the monsters which stalked over the
earth, or crawled through its fens and marshes, are sud-
denly overwhelmed by the deluge which was sent to de-
stroy the human monsters who did * evil in the sight of
God.' Antediluvian remains of animals are found in
Siberia, India, England, France, and Germany, and in
various parts of America.

In considering the ruins of the deluge, we must not
fall into the error which has been too common, of consid-
ering all fossil shells, and other organic remains found
imbedded in rocks, as marks of that event. It appears
probable, from observations made upon the rock strata,
that previous to this, the earth had undergone many
changes ; fire and water had been active in decomposing
and crystallizing the mineral substances on the globe,
and many animals and plants had become petrified and
fixed in their rocky beds.

The process of petrification consists in the gradual de-
cay of the original substance of an organized being, while
the place of the particles which pass off in a gaseous or
other form, is supplied by stony particles, until the whole
mass is thus changed. Some waters containing lime,
possess the power of petrifaction in a high degree. The
lime becoming concreted, takes the place of the original
substance. Shells are often found petrified ; they some-
times occur in large masses forming rocks, termed shell
limestone.

It is not within the scope of these lectures, to enter
deeply into geological investigations. So many impor-
tant facts and interesting observations crowd upon us,
when glancing at this subject, that the longer we dwell
upon it, the more it seems necessary to say. I must,
however interesting the theme, hasten to bring to a close
our remarks on Geology, and with this, our observations
upon Natural Science in general.

We have spoken of primitive, transition, and secondary
rocks ; of the great primitive ocean which, as is supposed,
once covered the face of the whole earth while it was yet
* without form and void.' We have remarked upon the
prevalent opinion of the gradual formation of the different
classes of rocks, the changes which the earth must have
undergone, previous to the existence of animals or vege-



232 GEOLOGY.

tables ; and that great and sudden catastrophe which,
with the exception of Noah and those who were with him,
buried in one vast, watery grave, the whole race of or-
ganized beings, including man, and beast, and the vege-
table tribes.

Everywhere upon and beneath the surface of the earth,
are to be found traces of the deluge. Masses of clay, sand
and shells, mingled with bones and skeletons of huge ani-
mals as well as those of a less size, can be accounted for on
no other supposition, than that they were thus indiscrimi-
nately thrown together by the rushing of mighty waters.
Caverns are discovered whose floors are covered with the
bones of hyenas, wolves, bears, and other beasts of prey,
who seem to have rushed together into these retreats, to
avoid the impending destruction. From the appearances
of the gnawed fragments of bones, it would seem that
they fell upon, and devoured each other. These remains
are covered by a light mud, evidently washed over them,
as the waters of the flood were subsiding.

The period before the flood is termed antediluvial
(from ante before, diluvium flood) : thus, those animals
whose remains are found only in the oldest rocks, are
called antediluvian relics. The ruins of the flood, the
land which was then formed, and all appearances which
seem the result of that event, are called diluviaL The
various geological changes upon and beneath the sur-
face of the earth which have taken place since the
flood, are called post-diluvial. The deposites of soil
or other changes effected by water, are called by the
more general term alluvial.

Besides the three regular classes of rocks, and the va-
rious kinds of alluvions, there is another formation con-
sisting of what are called Basaltic or Superincumbent
rocks. These lie over the other rocks in strata not con-
formable to them. They are supposed by most geologists
to be of volcanic origin: they are Amygdaloid, which is
an aggregate of hornblende particles of a dark gray or
brown color, and Greenstone trap, which is an aggregate
of hornblende and felspar. The Giant's Causeway and
Fingal's Cave in Ireland, and the Palisadoes on the
Hudson river are composed of Basaltic or trap rocks.
There are also other remains of Volcanoes, as lava of



GEOLOGY. 233

various kinds, either dark colored and almost homogene-
ous, or of cemented grains, or whitish lava, consisting
chiefly of melted felspar, and called Trachyte.

The various layers of clay, sand, and marl, which are
supposed to have been formed before the deluge, have re-
ceived the name of the Tertiary formation. The word
Tertiary, signifying three, is given in consequence of this
lying over the secondary formation.

This formation which is very extensive in France and


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Online LibraryLincoln PhelpsLectures to young ladies, comprising outlines and applications of the different branches of female education, for the use of female schools, and private libraries → online text (page 20 of 27)