Bloomington herald. [volume] (Bloomington, I. T. [Iowa]) 1840-1849, 1841-04-23
For the Herald.
GEOLOGY OF U:a-..y'O. L.

1t is the province of Geology to investigate
tie causes which have produced the various
phenomena Of physical geography. which en-
traces within its limits, among the many d.
,isons, those which relate TO the elevation
ind depression of the various parts of the
sarth's surface. to produce mountains and val
,eys, the extension into plains, and the frac-
lures into which the crust of the earth has
been rent. The dissimildr conditions that the
lsuvface Of the earth presents is owing to the
Diligence in its geological structure, from
which we learn that the constituent elements
of which it is composed are not uniformly con-
tinuous in all directions. In one district of coun-
try the lgeologist traces the course of various
rock; in second he finds strata ofcay and mari;
ia third, gravel and loose sand, while alter
nate laysrs Of sandstone and limestone are
found in another; and no less different are the
mineral contents Of these several formations
lead, clipper and zinc are found in one vain !;
| in another coal, and in third salt and gyp-
sum: willie iron, the most useful mineral, is
found in almost all the series.
The mineral materials Of the earth have
passed through various stages Of change and
revolution, during which, the strata of which
its surface is composed, have been alike affect
ed an examination into which discloses a
regular order in their superposition.
| The principal materials of all strata are the
earihs of flint, clay and lime. either OF which
10 a state Of purity is barren and unfit for cul-
| tiyation, but are valuable as the movements of
the waters, in transporting Them to their pres
emf locations, have caused them to be inter-
mixed in such manner and proportions as are,
in various degrees. favorable 10 the growth of
the different vegetable productions.
| The geological structure Of the earth IS
found to be constant, that is, the superpositlon
of the rocks is uniform-the succession in
which the several strata overle eachother is
universally the same. Commencing at the
lower surface are found granite and crystalline
rocks Of similar character. Next above them
are The primary FOSSIL ferrous rocks. Still above
lie the secondary rocks, including the noun
tain limestone and bi,uminous coal-measures.
Above the secondary rocks occur the tertiary
series. Immediately resting on them are found
the recent deposites, such as occur in river bot
toms.
1t is owing to this invariable order of
succession, and the knowledge that certain
minerals are exclusively found in certain for
nations. that biologists are enabled to predict
where the various minerals are TO be found
and where not.
Such an outline / have thought proper to
|
furnishing your readers, from Or. Owens Re-
port of Geological Exploration of Iowa and
Wisconsin, made during the year 1889, under
the direction of the General Government,
task which that gentleman was every way
qualified to perform, and which has resulted in
bringing TO light knowledge of the vast
sources of mineral and agricultural wealth
that this highly favored r'glon is found to pos
sess. In this enterprise the Principal Agent
was assisted by that interchangeable scholar and
| devOtee Of science, DIR. Locke, Of Cincinnati,
who has done more for the cause Of science
than any other Western man.
The region embraced in this survey or ex
ploraiion, is situated on both sides of the Mis-
sissippi river, and between la,itudes 40 and
43o; commencing at the mouth Of Rock Rv-
er, at Davenport, and extending to the mouth
of the Wisconsin, at Prairie du Chen; aver
aging in width 100 miles, and extending over
a surface Of ii 900 square miles.
| GEoLooICAL FEATUREs.-The SECONDARY for.
nation prevails generally throughout the
| Western States, which series comprehends
various subdivisions of distinct character and
invariable succession, which, in turn, have
been again subdivided. One of these subd-
Visions, the mountain Limestone, predominates
throughout the explored district, and to which
|
are referible. These subdivisions H. the West
err States generally vary in thickness from
100 to 1000 feet, except the cliff limestone,
which in many districts is hardly distinguish
able, ard seldom exceeds 100 fee, in thickness;
while in the lead region it becomes the most
remarkable, important and bulky member of
| the group, frequently attaining thickness of
| more than 500 feet; at the same time the I'M
DERIVING blue limestone, which in Ohio, is fire.
quently found 1000 feet in thickness, here
dwlndles down. to 100, and is many times en-
| llrely wanting, as is also the black slate and
| fine grained sandstone. This peculiar devel-
| opment of one of the mountain limestone
group is believed to be confined principally, if
not entirely, to the region explored.
The meteorological character of this region
belongs to the secondary series, and is confined
to the cliff limestone group, in which forma
tlon the ores lead, copper, zinc, and iron are
exclusively found. This cliff limestone, so
called from lis bold external appearance, which
cannot fail to attract the attention of the most
superficial observer in passing down the beau
tiful Ohio, or up the majestic Mississippi, is
OF magnetism quality, yielding from IS to
40 per cent. Of carbonate of magnesia. 1t is
from this that the epson salts of commerce
are manufactured.
This survey has resulted in showing stri-
king similarity (almost IDENTIFY between the
Amerscan and English lead regions. This
limestone is usually of light graylsh yellow,
passing into brownsh or reddish yellow
when exposed TO the action of the weather;
its specific gravity varies from 2.65 to 80,
and is found in three several beds, the upper
being more regularly s,rali6ed, more rich in
silicious fossils, containing ebert. and 1inty
rocks and hon ore, but rarely any lead. The