The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1885-10-17
THE SOURCE OF BLUE CLAY.
Professor Browns Lecture to the Geo.
logical Class of the High-School.
The Great Inland Sea of Pre- Historic Days
The Formation of the Sand Hills
on Lake Michigan's Shores.

DR.. R. T. Brown lectured yesterday morning
before the section in geology at the High-school
giving some account Of the survey of Hancock
county, which he is conducting for the State
Biologist and which will be published in the
geological report for 1886 1t will be remembered
that these reports are to be published every two
years hereafter. instead of annually, as hereto
fore. DR.. Brown said that his report would be
valuable mainly for establishing the system of
drainage for the county. DR.. Brown wrote of
Marion county for the reporto 1882. He says the
general features of Hancock county similar
20 those of Marion; it is covered with glacial
drift, and underlad with fhe blue clay. The gen
sral slope of the edrock is from north to south.
Soaring it6e west and this slope amounts
TO about ninety feet for the county, enough
so secure ample drainage for the many swampy
areas OF the county. Between these swampy
areas, which are made up of deep black peaty
SOIL lying on the blue clay, are wide ridges of
true yellow bowlder clay, deposited from the
great glaciers which once swept over the State.
This peaty soil is two to four feet deep, and in
dry autumns, has taken fire and burned, leaving
deep beds of ashes. The county bitches are some
of them several miles long; they run with
strong current, clearing themselves easily. Some
of them are seven feet deep and twelve feet
wide. The bottoms of the bitches are covered
with gravel; and the farmers often ask where it
comes from, the blue clay through which the
bitches are cut is composed of about 60 per cent
pure clay and 40 per cent. of fine white
quartz sand closely mixed together.
The answer is that the gravel is the leavings of
dne pebbles sorted from the clay as the sand
and fine mud carried on down the ditch.
In some small parts of the county, the powders
are so thick that $50 worth of dynamite is re-
CURED to clear them from a small area; some of
the powders are as large as q small schoolho
Regarding the source Of this blue clay. which
is vexed problem for the geologist Of North
America. and to which Dr. Brown has given
years of study. he said: This great area of clay
extends from the Alleehenies through Ohio, In
diana, Illinois and Iowa, thousand miles, to
Nebraska it is from one hundred to three hun
dred miles wide. 1t lies the bedrock of the
country, and is separated from the rock only by
layer of ground from two to four feet thick.
This clay is about twenty to thirty feet thick
in Marion county, and seventy,fve, to
Indeed, the southern part of Lake Michigan is
excavated as far north as Milwaukee, at least,
from this blue clay. Lake Michigan was in early
times sixty feet higher than it now ia, and ex-
tended forty or fifty miles south Into Indiana
The great hills of sand which now festoon the
lake shore from Chicago around to Michigan
City. aud so on into southern Michigan are sim
ply the sand of the blue clay which has beer
sorted out by water, thrown up by the waves on
the lake shore, where it is caught by the winds,
and goes rolling, sand dunes, over the coun-
try. These sand dunes extend forty miles down
into Indiana. and mark the old shores of the con-
stantiy recedng lake BASIN" Here DR.. Brown
gave graphic account of his walking on the
sand out 100 rods into the lake at the mouth of
the Calumet river below South Chicago, and
until the water was up to his neck. but by that
hIC cfQH fha hIohnr
carried back, as it threw the sand on shore and
into reach of the wind.
DR.. Brown says that under this blue clay
there is usually soil and the remains of cone
bearing forest-pines, cypress and the like.
Tree-trunks were found III boring the we'll at the
angie at the intersection of ST. Clair, Alabama
and Fort Wayne avenue, and the water was so
permeated with the taste and odor of rotten
wood as to not be potable. Similar logs were
found under the blue clay at the old Fletcher
place. Fletcher place Church. this city.
They are not uncommon, and, with the soil
found with Them prove that there was great
terrestrial vegetation and dry land under the blue
clay. Cypress logs were found also under the
blue clay at Bethany Park this summer.
OF the origin of the blue clay we have not facts
enough to form theory; 1t cannot be studied
locally, but must be undertaken by both the
State and the general government.
DR.. Brown had been invited by the United
States Geologist to formulate his views as to
the source of the blue clay tor the government
He is satisfied that it was never brought from
the north by the action of glaciers, as is the
case with the layer of yellow clay and powders
which lies above it. 1t was made by the break
ing up of clay states and sandstones 1t must
have been deposited by quiet waters as it is as
evenly bedded as the sedimentary rocks
But unlike them itcontains no fossils and there
is material better adapted for the preserva
tions of fossils. either fresh water or marine If
from an inland sea- it was deposited before the
glacial age. Now there was such a sea at the
close of the tertiary age, and it extended from
the Gulf of Mexico to Hudson's bay And at the
close of this age the western mountains were
elevated, carrying up the stratifed rocks of the
tertiary age, until the granite crests broke
through and appeared at the SUBMITS. DR..
have furnished the material of the blue clay,
and that these seas were lifeless, as the water
saturated with sui phur acids from the vol
.canic eruptioDs of the great West which are now
dying out. as the geysers of the Yellowstone.
This would account for the sulphur in this clay
which has united with the ever-present
iron of all soils, and so has
formed the sulphur-iron salts which per-
meate this clay and give it its red color
when it is baked by fire, and the iron appears as
an oxide. This is DR.. Browns hypothesis Of the
origin of the blue clay. For an octagenerian Dr.
Brown is remarkably well preserved and has the
strength and enthusiasm of youth of twenty
He thinks nothing of walking over to Hancock
county and back in day, and offered to walk
over there with the State Geologist when he
asked him in what part of the State Hancock
county is to be found DR.. Brown is an enthusi-
astic talker and has difficulty in interesting
school youth in the most vexed problems of
dynamical or structural geology.
Work-House Employees.
The County Commissioners have confirmed