The Mankato free press. [volume] (Mankato, Blue Earth County, Minn.) 1879-1924, 1907-02-22

formed III alternate layers at MankatC
and east. the little Shell animals form
ing the limestone and then storms wash
ing sand over them. when the shells
would form again to depth OF per
haas eightee minches. and so on laye
after layer alternately. The same
stone that is found at AIankatO il
found at st. Paul and further east
The white sandstone found at the
mouth of the Blue Earth river extends
downward 1000 to $500 feet, after
which granite is encountered. This was
found to be the ease when Perry Iim-
norman and his partners sunk THEN
well near Alinneopa after natural gas
The sandstone at the mouth of the
Blue Earth river is callel Potsdam
sandstone, and is the same as at
| POtsdam, New York. and i'll many other
localities. 1t outcropS at Spring Island
ut Rapidan Mills, and in the banks
of the WatOnwan and lie Sueur rivers.
Artesian Supply Inexhaustible.
Til" speaker showed the significance
of the Potsdam sandstone and glass
rock found aboumt Mankato on the
water supply of the city through the
artesian wells. He said that the ar
tesian water supply is practically mex
haustible, because of the dip of the
rock formation from west and south
and the sandstone layers between the
harder lime and impervious limsetone
layers. The supply for the wells comes
from the rivers alone, as there is no
surface seepage because of the hard
shale. The rock formation dips so
distinctly to the north and east that
the further in those directions one goes
the deeper the wells must be. AT St.
Paul the flowing wells are from 1880
tho 1000 feet deep. 1t is not de-
sirable to have too many wells close
together, as that reduces the pressure
upon each one, but they should be
spread out over the surface as far
apart as possible.
Cheap Water Power.
DR.. Hielscher advised the street rail,
way company to run line to ST. Pc.
ter, and to drill flowing wells near
Joseph Salfer's farm, Henry Heinze-
mans farm and at Mankato Junction
and run their combined flow into
channel where it would have fall of
siNty-iive feed down a gulch to the
river. Water power would thus be
had for factories.
The sandstone here has no value be-
cause 1t Is breakablc, but if it had a
little iron mixed with it. it would
make red sandstone like that in the
j.. L. Hunt building OH jackson street
and would be very valuable. There is
glass in stone, but Mankato is too far
from natural gas to make it profitable
to try to manufacture it. The lime
stone is made of shells ground I'D.
Dolomite, and is sandy and impure.
The wavy line of the lime and sand
stone layers is well illustrated at the
Jefferson lime kiln on the Great West
ern road. The limsetone is formed of
shells, sponges, corals, and extends G5
to 100 feet deep here. 1t is fissurel be-
cause of upheavals
Clay Deposits Scanty.
Dr. Hielscher said that he did not
think that there are large enough clay
deposits III Mankato to warrant the
erection of large tile factories. etc. ey-
cept for the boulder clay in the bluffs.
which would be all right were it not
Tor the limestone pebbles in it, which
1t IS expensive to remove
The club gave DR.. Hielscher a vote of
thanks.
DIR. F. J.. Schmauss asked whether
the sandstone here would make a good
road.
Macadam Pavement Material.
DIR. Hielscher replied that it would
not, as there is no binder material in
1t. Nature always uses iron as
coloring material and for binder but
IN the sandstone here there is no iron
or very little. Still there is the finest
material here out of which to make q
street that God ever provided.
The trouble has been that the residents
have tried to improve upon nature and
have failed. By combining the lime
stone with the rel Indian lake gravel
a strong wearing surface would be
formed. Geolog.cally speaking, the fol-
lowing specifications should be follow
ed: ENcavate to depth of sixteen
inches, and then fill with twelve inches
of the toughest limestone riprap that
can be found. and break if necessary
Then fill with four inches of crushed
limestone rock, to go through two
inch ring, and then place Indian lake
screened sand upon the broken stone
and let it fill the interstices between
the rock. Use water to wash down and
roll with heavy roller. The lime
stone contains quick lime and the In
dian lake sand contains iron, and bv
the two we would be imi-
Eating nature in providing a binder.
The materials should be well rolled and
crushed together A street would then
be had that would never wear out. but
1t must be cared for and cleaned the
same as brick or asphalt pavement.
Clay In Cambria.
W. ID. Willard asked about the ere.
tacious clays.
DIR. Hielscher replied that there are
extensive beds of this in Cambria and
hudson, that might be utilized for tile.
orick and terra Gotta, although a prac
Cical burning test is the only one that
Will decide this. At Birch Collie three
are extensive beds, and the time is
coming when there will be large tile !
.,lAx. I