20 Geology of Peoria County. 
They were pressed down by an increasing weight, which became an irresistible 
force; taking with them huge boulders, which ground the rocks beneath them, © 
also carrying with them, and upon them, large accumulations of debris, torn 
from the mountain sides as they passed down. This debris was spread over the 
country as far south as the Ohio River. 
Icebergs are also regarded as having been largely instrumental in the distri- 
bution of our drift deposits. They floated upon seas covering the land during 
the latter portion of the existence of the glaciers. It is not improbable that 
they floated upon the great fresh water lake of more recent time; this lake 
having been continuous from the age of the glaciers. 
To what depth the drift accumulated we have no means of determining. 
That the surface was more than one hundred feet higher than now, is evident 
from the fact that the mound at Elmwood is more than one hundred feet 
higher than the average surface of country surrounding it. This mound con- 
sists of stones, gravel and sand, which was too heavy to be washed away with 
the finer clays and sands around it. 
It is thought that the glaciers must have gouged out the basins of the 
northern lakes. If this is true, it is not unreasonable to suppose that Peoria 
Lake basin was gouged out in like manner. For the rock and coal beds have 
been cut out and carried away, for a distance of some twenty miles in length 
and three or four in width along the west side of the river. 
The lake has been some four miles wide, and several hundred feet deep. 
The water filled all the space between the bluffs to their surface, or near it, 
for a long time, as evinced by the erosion of the sandstone that crops out a 
few miles below Ottawa. During the time in which the Lake which covered 
our county existed, our lake basin was again filled with new deposits. These 
are called “ modified drift.” 
When these waters passed away, the channels were again washed out, and - 
left in the present condition of valley, and river beds. But for a long time 
subsequent, the volume of water was so large as to cover the valley to a con- 
siderable depth, from which came the materials which formed the plateaus, 
upon which Peoria stands. This is called the “Terrace Epoch.” 
Thus, we have the phenomena of the drift deposits. They vary in depth, 
from a few feet, to more than one hundred. More than one-half have proba- 
bly been carried away by the rushing waters. But enough remains to answer 
the purpose of the Great Designer. 
They are the last formation that prepared the earth for the fullest expression 
of the Creator’s designs—the habitation of man—who in himself was the 
fullest expression of the Creator Himself. 
DYNAMICAL GEOLOGY. 
In the dynamica! geology of the county I have but little to report. There 
are found some “faults” in the coal beds. At Sword’s lime-kiln on the north- 
east quarter of Section 10, in Limestone township, was found beneath a stra- 
tum of limestone ten feet thick, a fissure twelve to fourteen inches wide, filled 
with heavy spar (Barytes Sul.) and zine blend (Zinc Sul.) 
These minerals are not usually found in the carboniferous strata, but belong 
to the lower Silurian. This opening was doubtless made and filled before the 
deposition of the limestone above it, by forces probably from beneath, and the 
minerals in a fluid or semi-fluid condition forced up into it. 
At the Chase quarries, on the Southeast of Section 5, Akron township, the 
limestone beds have been forced up to within three feet of the surface of the 
prairie. The area thus forced up is so small, that the upward curve of the 
bed is perceptible; showing a number of breaks about two feet wide atthe 
top tapering down to a point at the lower side. 
