Dr.. Smiths Lectures on Geology.

NO. VII
{"character_count": 6142, "word_count": 1093, "ccnet_language_score": [0.9667999744415283], "ccnet_perplexity": [990.7000122070312], "fasttext_language": ["en"]}
circles of the coral reef surrounding an laahu OF
.belrer;,o +, one bay of water-copied from draw
ings made by Capt. BEEcEEY ia bis Voyage round
the World. For long time, ne said' II was
wonder how these attols could be toruled-as al
ways Just outside the circle the water was found
to reach much greater depth than the insects
from the immense pressure ct water above, cou!o
possibly work The commonly received conJec-
iure, which be thought least plausible, Is that
these are the of volcanoes-the insects hav-
ing built upon the sides OF the mountains before
uphcava and continuing to build as they gradu-
ally subsidized Still the fact that there is always
in the circles one opening to the sea and sometimes
more. operates as an objection to this theory. Mr..
Lvell accounted for it by supposing that streams
Of fresh water flowed down The sides of the noun
tain after its upheaval; and as 1t is known the
coral insects will only work where the water is very
salt it would naturally result that gaPes or openings
would be left in the paths Of these fresh water
streams Some reefs are of great extent-one upon
the coast of Newfoundland reaching many thou
sand miles. There are few coral reefs in the At
antic. though they have existed largely upon this
Continent. The limestone wllichtoruls the Cave of
kentucky mas evidently been made up OF coral :
and we are of course led the conclusion that the
climate here has been far warmer than now. This
whole theory OF coral formation, Dr.. S. said, was
verv b.autiful: but he wished for its more rigid
proof.


Or. S. presented very fine representation OF
the Natural Bridge of Vitsinia-ot which the ex-
planaton, he said, was very plain. lhe whole
country being under water the she'll fish and other
animals, encountering huge bank of sand wrong ut
upon either side till they came to its summit, ana
then upon its top--thus forming an arch with sand
beneath Then came the upheaval OF the whole
country; rains washed away the sand and left the
arch complete, as we HOW find Ait. Thus, also,
we're the kentucky caves formed and nothing is
more natural than to suppose that ages hence,
when the Banks of Newfoundland are upheavcd
and the sand washed away, we shall have remain


ing there caves and arches OF the same description.


Coming 10 the Geology of the United States,
Or. S. pointed out upon map its prominent tea
lures The first thing that strikes the eye, he said,
is that the whole country Is series OF Penlnsulas,
aad may one day, by the union of the Mississippi
and the Lakes, have been an island. All New


England except Cape Cod, is made up of primary
rocks, composed of granite-or of rocks OF that
description. Cape Cod is tertiary Long Island
is tertiary, and then all Westward, until you reach
the Highlands, is primary. The sea here washes
the granite as it does not further South All the


section along the coast of the Atlantic, reaching
back until you come to the tall OF the rivers, Is


tortiary. down TO Alabama thong many geologists
think that Florida is coral limestone. The New
England primary passes Westward of this tertiary
and when that region is reached we have the best
portion Of the United States-the most healthy
and productive and the proof Of this is that the
stoutest men are produced.


When we go back of the Highlands, get to
the Trenton limestone and the Sllurlan or primary
Fossiliferous formation. This has been traced as
far west as Iowa; and SO gentle has been the up
heaval of the country that there is scarcely trac
ture to be found through its whole extent. On the
upper branches of the Potomac, in the Cumberland
region, we find all the strata one above the other,
and the whole upheaved 1000 feet above the level
of the sea. Here, then, the coal may be dug
above ground; and the miners are spared the
trouble, which causes so much difficulty in Eng


land of pumping out the water his adds greatly
to the advantages of the district


In speaking of the Geology of this Island, DR.. S.
said that at the Battery the rock is gneiss though,
before we get out of the enclosure, we come to di
III.
and at Union Place the granite crops out, and
passes through the gneiss. A little above this we
find serpentine aud at Manhattanville deep cut,
ascending from which we meet with hornbende


1t is fact, DR.. S. said, that the Island is al
ways subject TO autunnal diseases; and this fact
puzzled physicians for long time-cspecially as
it was found that as the city extended It's limits 1t
became more and more healthy. There seemed to
be no water-no psols or lake, to explain the tact
but the Geology Of the Island made it plain. The
whole Island is series Of basins and the water
falls through the soil and lodse upon rock, be-
meath which it cannot go. Thus 1t remains and
makes the atmosphere impure. As the city ex-
tends the water is prevented from settling down,
but runs off through streets or cutters.


The last subject connected with individual rosks,
Of which DR.. S. said he should speak, was the
Palisades upon the other side of the river, which
rise to hight of 700 feet, and are 5ub,tratihed by
old red sandstone, as may be seen at Hoboken
when the tide i. low That they were produced
by subterranean heat no one doubts. The matter
was formed beneath New-Jersey and thrown up
By some volcanic action; but it seems singular
that it should have cooled and remained thus up
right, like a wall, instead of floating off and de-
scending gradually.


1t seems necessary, he said, to suppose that
there must have been deep channel-two parallel
ridges of aud-between which the liquid matter
flowed and when it was cooled, the sand was
washed away by the river, and the face of the Pa


sades was left standing.


After few remarks concerning the general
geological structure of the country, Dir. S. said
that it remained to consider the effect produced
upon the Earth by animals upon its surface; and
proceeded physically TO define animals organ
lied beings, provided with s,omachs for the diges-
ton and assimilation of the food upon which they
live Metaphyscally defined, he said, they were
hsings conscious Of their own existence-suscepti-