Alexander Winchell.

Report of a geological survey of the vicinity of Belle Plaine, Scott County, Minn. online

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Online LibraryAlexander WinchellReport of a geological survey of the vicinity of Belle Plaine, Scott County, Minn. → online text (page 1 of 2)
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ST. PAUL, January 23d, 1872. )

Hon. W. II. Yale,

President of the Senate.

SIR: On the 2Stli day of February, 1870, a law was
passed by the legislature and approved by the governor
entitled ' ' An Act to aid in the development of Salt Springs
at Belle Plaine," which donated six sections of the State
salt lands to said company, on certain conditions. [See
chapter 114, page 421 of the special laws of 1870.] These
conditions were afterward complied with by the company,
and the lands conveyed to the company by the State, as
required by the terms of the law.

On the 6th day of March, 1871, " An Act to further aid
the Belle Plaine Salt Company in the development of Salt
Springs at Belle Plaine" was passed. [Chapter 129, spe-
cial laws of 1871, page 365.] This act contained a proviso
that there shall be a geological survey of the springs and
adjacent neighborhood, and that the provisions of the law
giving further aid shall not be operative unless the report of
the geologist shall be favorable.

Prof. A. Winchell, State Geologist of the State of Michi-
gan, was designated by the Governor to make such survey
and report the results thereof to him. Prof. Winchell
accepted the appointment, made the survey in June last,
and filed his report with me on the 17th of that month.
As the survey and report were made pursuant to an act of
the legislature, and as the report contains the recommenda-


tioritf aid conelasioi?s of tlie geologist, touching matters of
public policy, I deem it my duty to lay it before tlie legisla-
ture, for their consideration, and have the honor to enclose
the same herewith.

Should the legislature be of opinion that, notwithstanding
the report, the probabilities of a successful termination of
the enterprise are sufficient to justify its further prosecution
at the expense of the State, with that object in view, or if,
on the other hand, it should be thought, though such prob-
abilities should be excluded, yet that work should be
prosecuted with reference to other possible results, and in
the interest of science, then further legislation might be
required. Very respectfully,

Your obedient servant,



SIR : In pursuance of an appointment from Governor
Austin, dated St. Paul, March 30, 1871, I have made such
geological survey in Minnesota, and especially in Scott
county as seemed requisite to enable me to form an opinion
ot the prospect of obtaining brine at Belle Plaine, or in its
vicinity, of sufficient strength to sustain the manufacture of

For the information of your company, I proceed to state
the facts and general principles which have guided me to a

Common salt and its solution, brine, being a product of
chemical reactions in the primeval ocean, and not, to
any considerable extent, the result of recent causes, its
original home was the ocean ; and as a geological product,
its place is amongst the other sediments and precipitates of
the sea, which make up the body of stratified rocks. With-
out pausing to explain the circumstances under which we
believe the saline particles have become mingled with
mechanical sediments in the progress of rock-making, it may
be interesting to know that all formations since the begin-
ning of Palseozoic Time, and not unlikely from an earlier
period, are liable to be found saliferous.

That a formation originally saliferous may have remained
such to the present day, it must always have preserved,
since solidification, such an attitude that fresh waters have
not been able to filter through it and wash out its salinity.
That is, the formation must always have preserved a dish-


like configuration. It must be stated, however, that in
cases where the mother-rock of the brine is underlaid im-
mediately by a porous formation, as sandstone, the latter
generally becomes saturated with the teachings of the salt
rock above, and serves as a reservoir to be tapped in the
search for supplies of brine. The mother-rock of brines
is apt to be argillaceous and gypsiferous as well as salifer-
ous ; and unless beds of sandstone be interstratified, it is
useless to expect great supplies of brine, however strong, in
this formation. The storehouse of its brines is below.

Natural brines of workable strength and quantity have
also accumulated in beds of superficial gravel and sand, in
situations where such deposits have received the leachings
of a salt formation. This is the situation of the brines of
Onondaga county, New York, and the vast deposits along
the eastern flanks of the Sierra Nevadas.

The principal brines of the United States have been ob-
tained from the following formations, beginning with the
lowest :

Salina Group. This contains rock-salt at Goodrich,
Ontario, and Alpena, Michigan. Brine accumulates in its
porous strata, and supplies wells at St. Clair, Mt. Clemens
and Port Austin, Michigan. Its leachings saturate gravel
beds which supply the extensive works of Onondaga county,
New York.

Marshall Group. This supplies the numerous wells
along the Saginaw Valley in Michigan. It is simply a
receptacle of brines filtered from the overlying formation
known as the u Michigan Salt Group," and found in no
other portion of the United States.

Carboniferous Conglomerate. This is the reservoir of
brines supplying most of the wells in "West Virginia, Ohio,
Indiana and Illinois. It also supplies some of the shallow
wells in the Saginaw valley, Michigan. The source of the
brine is believed to be the coal measures overlying.

Jbfesozoic Formations are known to be highly saliferous
in Kansas and Nebraska and other parts of the "West ; and
probably the salt of northwestern Minnesota is derived from

these sources. The great salt deposits of Nevada are of
Mesozoic age as also those of central Europe and Great

The problem to be resolved in reference to Belle Plaine
was, threefold, 1st, whether the age of the rocks approximates
to that of any of the known saliferous formations of the
United States; 2d, whether the altitude of the strata is
such as to have retained their primitive saliferous constitu-
ents ; 3d, whether the situation is such that the filtering
ot a saliferous formation could have accumulated in beds of
sand and gravel resting on the surface of the rocks.

"With the view of determining the geological age of the
underlying and neighboring strata, I made geological exam-
inations of various points along the valley of the Minnesota

At Kasota, 30 miles from Belle Plaine, is quarried a higlv
ly magnesian limestone of a reddish creamy color, which
outcrops at an elevation of about a hundred feet above the
river. At Ottawa, 16 miles from Belle Plaine, up the river,
is quarried a similar stone, a little more tinged with red,
which outcrops at an elevation of 75 feet above the river.
I did not visit these two localities, but saw abundant ex-
amples of the rocks. The latter locality, morever, has been
described by Dr. Shumard.

A sample of the stone from Ottawa, crushed and treated
with dilute sulphuric acid, effervesces with great briskness,
and leaves an undissolved residue amounting to but an insig-
nificant percentage. It is not, therefore, a sandstone, though
its granular character gives it a somewhat arenaceous aspect,
and the rock is sometimes regarded as a sandstone. This
aspect and the buffish color are common to magnesian rocks.
In fact, the presence of magnesia is readily proven in this
case, by the distinct flavor of Epsom Salts detected in the
solution. Chemical analysis shows that the usual composi-
tion of this formation, in Minnesota, is essentially one pro-
portion of carbonate of lime to one of carbonate ot magnesia.
Dr. Shumard has given us the following analysis of a sam-
ple of the rock from " White Eock bluff," which I judge to


be the Ottawa o.utcrop (Owen, Geology of Minnesota, &c.,
p. 484, Note) :

Carbonate of lime 58.65

Carbonate of magnesia 29.15

Insoluble matter 7.25

Alumina oxyd of iron and manganese 1.55

Water 2.65

Loss 0.75


At Keystone, four miles above Belle Plaine, at an eleva-
tion of 60 or TO feet above the river is an outcrop of mag-
nesian limestone similar to that at St. Lawrence, of -which
more particular mention will be made. A slight outcrop of
the same occurs one and a half miles below Belle Plaine, on
the land of William Hinman. At St. Lawrence, which is
about four miles below Belle Plaine, and at an elevation of
about forty feet above the river, occurs the following series
of strata, enumerating from above downward and designat-
ing the lowest visible stratum as " A " :

F. Magnesian limestone, speckled and mottled with
green, and having numerous greenish partings. Greatly
shattered 2 feet.

E. Magnesian limestone, huffish, thick-bedded, vesicu-
lar. Contains crystals of brown spar. Quarried for build-
ing 4 feet.

D. Magnesian limestone, reddish-tinged, hard, fine,
crystalline 2 feet.

C. Magnesian limestone, irregularly bedded, buffish,
containing green specks probably of silicate of iron and
fucoidal casts 4 feet.

B. Arenaceous greenish shale, with partings of light
clay 8 inches.

A. Buffish, magnesian limestone in thin layers. Thick-
ness unknown.

From these observations, it appears certain that the rst
bench above the bottom lands of the Minnesota Yalley, be-
tween Kasota and St. Lawrence, is underlaid by the "Lower


Magnesian Limestone" of Owen, which is probably the
equivalent of the "Calciferous Sandrock" of iSTew York.
It appears, further, that in the distance of 3-i miles, it dips
down the river at such a rate as to be about 60 feet nearer
the water at St. Lawrence than at Kasota supposing, as
is probable, that nearly the same part of the formation out-
crops at each locality.

Passing from St. Lawrence northeastward down the val-
ley to Brentwood, we pass a region known as Sand Prairie,
characterized by an upland, rolling surface, and a poor,
sandy soil, without tree or shrub. It is apparently a deposit
of detritus arising from the abundant disintegration of some
neighboring sandstone.

Turning southward, up Sand creek, we find the sandstone
which has probably been the origin of these sands. By
examination in the beer-vaults at Jordan, and along the
various outcrops higher up the stratum, we find a section
somewhat as follows :

F. Sandrock, huffish, quite ferruginous, thick bedded.
Seen at the mill 6 feet.

E. Sandrock, ferruginous, thin and irregularly bedded,
friable and disintegrating, with many ferruginous seams,
crusts and concretions. In the quarry, 3 feet.

D. Sandrock, irregularly whitish or ferruginous, heavy-
bedded, obliquely and beautifully banded with iron streaks
and lamines. In quarry, 12 feet.

C. Sandrock, buffish, similar to D, but thinner bedded.
In the quarry, 8 feet.

B. Sandrock, hard and ferruginous above, soft, friable
and bufnsh-red, below. Falls of Sand Creek, 10 feet.

A. Sandrock, whitish, compact. In the beer vaults, 12
feet seen.

This sandrock formation, notwithstanding its considerable
elevation above the magnesian limestone at St. Lawrence, I
am; induced to regard as the Potsdam sandstone, whose
stratigraphical position 'is beneath the magnesian limestone.

At Dooley ville, 4 miles north-east of Jordan, is an outcrop
over several acres, of a buffish and reddish, coarse, silicious


sandrock, dipping about 2 degrees toward the south east.
Some portions are quite hard, and even vitreous, while the
lower portions rapidly disintegrate into a clean silicious sand,
of rounded transparent grains, beautifully adapted to the
manufacture of clear glass. The impurities would not pro-
bably exceed one-tenth of one per cent. This sandrock
should not he confounded with that at St. Paul.

This ridge strikes in the direction of the Little Rapids of
the Minnesota river at Carver City, which owe their exist-
ence to the unyielding strata, dipping there with the descent
of the stream. This conclusion supposes a considerable
swell in the stratification, to bring the rocks at the rapids to
the altitude of the sandstones at Jordan.

The thickness of the sandstone at Dooley ville is about 24
feet to which must be added, below, about 10 feet, exposed
in the neighboring railroad cut.

At NagePs limekiln, on the Louisville Prairie, about one
mile south of Merriam Station, we find another outcrop of
limestone in a bluff facing west, and re-appearing in an out-
lier a quarter of a mile nearer the river. The rock is very
irregularly stratified, and varies nrnch in hardness and color.
The prevailing colors are finkish and huffish. Some of the
layers are sandy, others magnesian, others ochrey and ferru-
ginous, others purely calcareous. Some portions are quite
resicular and abound in small crystals of brown spar. Thirty-
six feet are exposed in the quarry, and below this, a well
has been sunk 38 feet in the limestone, making a total of 74
feet. Below the limestone the well extended 24 feet in sand-
stone, which was at first hard, like that of Dooleyville, and
below, resembled the Jordan sandstone.

At Shakopee, the same formation exhibits an exposure of
20 feet, and is here also manufactured into lime. The lime
at these localities is of a slaty color, but is said to be of good
quality. White lime is sometimes manufactured from the
selected purely calcareous layers.

As this limestone seems to hold a place next above the
Jordan sandstone, and also considerably resembles the St.
Lawrence limestones, I am led to regard it as the Lower


Magnesian Limestone of Owen, though the top of the bluff
at.NagePs limekiln is probably TO feet higher than the quar-
ry at St. Lawrence, ten miles distant in a straight line, tip
the river.

From bagel's limekiln the strata resume the dip down
the river, and the next outcrop is of the overlying St. Peter's
sandstone, which is probably the equivalent of the Chazy
Formation of New York and Canada. This sandstone, at
Mendota and Fort Snelling, is capped by the limestones and
shales of the Trenton Group. The Chazy - and Trenton
formations bound the gorge of the Mississippi Itiver to St.
Paul and to the Falls of St. Anthony. Just above the falls,
the limestones thin out in the bed of the river, but continue
to appear, for a few miles, along fhe banks and at the high-
er levels. The Chazy sandstone disappears nearly at the
same time, and the magnesian limestone comes to the sur-

From the foregoing statement of facts it appears that the
region from St. Paul to Kesotah, and we may add, to
Mankato, is underlaid by rocks occupying the lowest posi-
tion in the Palaeozoic series, and beneath the lowest zone of
brine-producing strata known in the United States. This,
however, is not decisive against the existence of brine in
these strata.

It also appears that in a direction parallel with the axis of
the Minnesota valley, the strata present a slightly concave
conformation, which is essential for the accumulation of

In the direction at right angles with the valley a similar
conformation exists, and we know that from the mouth of
the Warajn river, northward, the Huronian rocks (next
beneath the Paleozoic) occupy the surface when not con-
cealed by drift, and the streams also descend from that direc-
tion to the Minnesota ; while on the east, the Potsdam sand-
stone, after passing beneath the Lower Silurian and Upper
Silurian strata, comes to the surface again in the valley of the
Mississippi river.

The following section presents a general view of the geo-


logical structure from Glencoe through Belle Plaine and
Hazel wood to the Cannon river :

1. HURONIAN SYSTEM [The dips of the strata are hypothetical.]

2. POTSDAM SANDSTONE Believed to be considerably eroded in the
valley of the river.

3. CALCIFEROUS FORMATION (Lower Magnesian Limestone.)

4. CHAZY FORMATION (St. Peter's Sandstone.)


6. DRIFT MATERIALS, represented as covering the whole surface
and partially filling the ancient excavation of the Minnesota river.
The two upper terraces at Belle Plaine are believed to be shaped by
the underlying formations, though deeply buried in drift.

The basin structure, as far as shown in this section, is
sufficient for the accumulation of brine, and it might be
looked for in the vicinity of Belle Plaine, were there not a
lower depression of this basin further southward, extending
into Iowa and Missouri. The shaly strata of the Trenton
group which overlie the central portion of the section, are
likely to be somewhat saliferous, and the brine, in such
case, would find its way to the Potsdam sandstone, and
flow toward the lowest depression of that formation. But
the nearest places of outcrop of the formation are in Sibley,
Carver and Nicollet counties ; and I cannot doubt that sur-
iace waters have saturated that sandstone for many miles
to the southeast of the Minnesota valley. * The search
for brine in this sandstone would therefore be reward-
ed only with fresh water. That water, in places lower
than the outcrop of the formation as along the valley
of the Minnesota river ought to rise to the surface. The
experiment of boring into it would probably resulc, therefore,
as at Chicago, in a copious Artesian well.



The foregoing statements show, 1st, That the situation
at Belle Plaine is geologically lower than any known Irine-
producing formation of North America; and 2d, That
even if the shales of the Trenton group should prove to
~be a saliferous formation the product is likely to accumu-
late uderneatha region far to the south. It must be added
that no accumulation is probable, even toward the south,
since the southern border of the basin is so depressed that
fluids have probably found a free circulation through it, and
most of its saline constituents have been carried away.

It remains to consider whether the situation is such as to
justify the expectation that the superficial sands and gravel
of the river-bottom at Belle Plaine, or its vicinity, have
become saturated with brine of sufficient strength to justify
the attempt to manufacture salt.

The superficial materials represented by number 6, in
the diagram before referred to, have accumulated in the
valley of the river at Belle Plaine to a depth of 210 feet.
They consist mostly of sand and gravel. These facts are
apparent from the following statement of materials passed
through in boring the existing well.

At depth Intervening
of thickness.


9 Soil and gravel.

9 9 Clay and gravel.

18 18 Sand and gravel.

36 54 Quicksand.

90 1 Coarse sand.

91 C Clay. At 93 feet, a piece of grapevine with


97 38 Sand, varying from quicksand to coarse

sand. At 114 feet, sand filled the pipe 12
feet ; at 125 feet, it filled 5 feet.

135 45 Gravel, quicksand, and coarse sand. At

144 feet the pipe filled 10 feet. At 168 feet
another piece of grapevine.

180 7 Blue Clay.

187 13 Rock fragments.

200 2 Gravel. Brine stood 18 by salometer.

202 8 Shelly rock.

210 Bed-rock said to be a sand stone probably

Potsdam sandstone (see diagram.)

Here is a favorable bed of materials to serve as a reservoir
for any brines wliick might escape from the outcrops of
any of the contiguous strata ; and some surface indications
of brine have long been known ; but, in boring into these
deposits no brine seems to have been reached of sufficient
strength for practical purposes. This may be either because
the supplying formation is insufficiently saliferous, or be-
cause the gravel beds are not underlaid by an impervious
floor of clay, capable of arresting the downward escape of
the brine.

Should this well be properly pumped, the strength of the
brine would probably be somewhat increased. It would be
desirable to pump it from the bottom, and also at the depth
of 180 feet, immediately above the seven feet bed of clay
the hole below being, in the meantime, temporarily stopped.
It is my opinion that if the strength could be increased to
50 or even to 45, the salt manufacture might be establish-
ed. The remoteness of this part of Minnesota from the
principal sources of supply of salt, and the cheapness of fuel,
would render available a very much weaker quality of brine
than could be employed in a region as far east as Chicago.
I feel it my duty to state, however, that / do not consider
tliis expectation very encouracjiny. The increase of strength
produced by pumping would not probably be sufficient.

As there are different methods employed for expressing
the strength of brines, it may be useful to add here that the
salometer expresses percentages or hundredths of complete
saturation. One hundred degrees expresses complete satura-
tion; 50, half saturation ; 25", one-fourth saturation, and
so on. " Percentage of salt" in brine is a very different
thing. " Eighteen per cent, salt" means that in 100 pounds
of brine, IS pounds are salt. Saturated brine contains about
25 per cent, of salt, and this percentage is equivalent to
100 on the salometer. Beaume's Hydrometer is a salom-
eter graduated to 26 instead of 100". The strength of brine
is also expressed by its specific gravity, which is its weight
compared with an equal bulk of pure water. Thus, if a
certain volume of water weighs one pound, the same volume


of saturated brine will weigh 1.2 pounds. Still another
method is to give the number of grains ot salt in one wine
pint of brine ; or lastly, to state the number of gallons of
brine required to produce a bushel of salt weighing 56

Natural brines always contain some impurities, and the sal-
ometer is affected by these in the same way as by common salt.
Hence some deduction must be made from the indicated
strength, depending on the proportion of impurities in the
brine. The impurities can be determined only by chemical

Below is an abridged table showing the equivalencies of
the various methods of expressing the strength of brines :

Equivalent Expressions for Strength of Brines.




Pef centage"


Gallons to



of Salt.

to 1 pint.

1 bushel.








































15. CO





























The nominal strength of the brines employed in the Sagi-
naw salines is about 80, but they contain a large percent-
age of chloride of calcium. The mean strength of the
Onondaga brines, in 1862, was 61. It is supposed the first
Oriondaga brine employed in the manufacture of salt did
not possess a strength above 40 or 45.

The prices of wood per cord in Onondaga county, have
been as follows : In 18-19, $2.00 ; in 1856, $5.50 ; in 1857,
$1.50; in 1860, $3.50; in 1861, $3.25; in 1864-, $3.50.
Anthracite coal became extensively used in 1857, costing
about $3.50 per ton, and reducing the cost of salt two or
three cents per bushel. One ton of coal, at Syracuse, makes
about fifty bushels of salt. The following table shows the
relative value of different classes of fuels for purposes of
evaporation :


Equal W't. Equal B'lk.

Maryland Bituminous 1,000 1,000

Pennsylvania Anthracites ..... 977 986

Pennsylvania Bituminous coals 951 938

Virginia Highly Bituminous

coals 850 757

Foreign Bituminous coals 801 741

White Oak TOO 610

Bed-Heart Hickory 700 592

White Ash 690 551

Black Walnut 615 486

Hard Maple 530 460

White Pine 362 298

Although I am unable, for reasons already stated, to
report favorably in reference to the prospect of obtaining


Online LibraryAlexander WinchellReport of a geological survey of the vicinity of Belle Plaine, Scott County, Minn. → online text (page 1 of 2)