The Barre daily times. (Barre, Vt.) 1897-1959, 1913-06-12
ONCE PART OF OCEAN.
Southern Illinois Has Geologic Indica
tons of It.

The results of a detailed investigation
and geologic survey of district in Hi
nols of great mineral Importance hay,
just been issued by the United States
geological survey in the form of a foliC
: OF the geologic atlas OF the United
, States, which the survey is gradually is
| suing in parts.
The district, comprising the areas
known as the Murphysboro and Herrin
quadrangles. lies in johnson, Perry
Franklin, and Williams counties, at the
south end of the great coal producing
AREA of Illinois. The folio includes topo-
graphic maps on q scale of about an
inch to the mile, showing the surface
features and the altitude of all points
in the area, and geologic maps, show
ing the character Of the rocks watch
tnderlie the surface, together with a
descriptive text The area lies in the
basin of Muddy river and is in part low,
fiat and swampy and in part rough
and rocky. The altitude ranges from
$50 to $50 feet above sea level. The
rocks are Carboniferous in age, which
means that they are many million years
| old-about half as old as the Oldest rocks
known. The term Carboniferous is very
appropriate, for rocks of this age in all
parts of the world contain much baron,
partly in the form OF coal. The LAYERS
of rock are nearly fiat but slope gently
TO the north and east.
The chapter on geologic history states
that ages ago southern Illinois was a
part of the ocean and that the sedi-
ment in the water slowly settled to the
bottom and later hardened into rock.
Now and then the area rose above sea
level for few centuries or thousands of
years. AT times the region was n great
swamp with luxuriant vegetation, and
Just as in such places to-day, the vege-
table material does not decay completely
but accumulates year after wear, so in
Carboniferous time the plant material
accumulated and later, when conditions
changed, this material became buried
under deposits Of sand and mud and FIN
ally was compressed into coal. Since |
time the region has been |
above sea level and has been profound
IL eroded by streams. which are eontin- |
ually carrying sediment away Less I
than million years ago. at time geo
logically very late in the earth's history, /
a great glacier crept down from the
North, bringing with it vast quantities
If stones and dirt that are now found
deposited over large area in northern
United States and Canada This glac-
er reached its farthest south in south
,rn Illinois, where it covered over a
thousand square miles south of the thir-
" eighth parallel. As it retreated or
he advent of a warmer climate it left
is load of earth. gravel, and powders
a I-,f -
tate. The powders are strikingly diff
erent from any rock to be found in 5
lace in the state and may be traced d. :
ectly back to their parent lodges in 5
anada.
Bed of An Ancient Lake.
One of the most interesting events !
-hich has been deciphered in the sur /
ev of this area is that in geologically =
acent time a large part OF it was the q
ed of lake. which is now extinct. The .
iscovery of this fact led to the search II
n evidences of other similar lakes and !.
any were found in southern Illinois =
nd western Kentucky. The lake beds
re very fiat except where they have IA
zen washed by streams, and the sedi- h,
ent deposited in the lakes is over 81
indred feet thick. In some places lake p
caches are as well preserved as if the :,
alter had only yesterday been tapping :,
rer them. Commonly these beaches are -
,ed for highways. :,
The most important mineral resource -
the district is coal, that mined at
being of very high quail :
Y. There are seseral beds of coal. es-
cially in the northeastern part Of the
ca. In the southwestern part there is
Ilv little coal
4 copy Of the Murphysboro-He rrin
60 NAV be obtained for - cents from 4
. Director of the Geological Survey,
ashington, ID. c.