Geology of Upper Illinois. 145 
To the traveller who enters the Illinois valley at Ottawa, after 
having been satiated with the boundless views of rolling prairie, 
no scenery can be more novel and enchanting, than that which 
he beholds between the mouth of Fox river and the town of 
Rockwell. The first striking object he encounters after leaving 
Ottawa, is Buffalo-rock, an interesting plateau, whose top corres- 
ponds in level with the high prairie, and whose sides are equally 
precipitous with the main bluffs of the valley. The area of Buf- 
falo-rock is about one square mile. The river sweeps directly past 
its southeastern base; while the canal, as will appear from the 
map, is carried along pekieun it and the north bluff of the valley. 
At a distance of about a mile from this insular elevation of prai- 
rie, and directly by the road-side, is situated one of those beauti- 
ful mineral springs (of whose chemical constitution we shall 
presently speak,) for which this part of Illinois is remarkable. 
Two springs break out within a distance of a rod, both of which 
occupy the same basin-like depression, whose surface is about five 
feet lower than that of the adjoining bottoms. The larger of 
these two springs discharges at least ten gallons of water per min-— 
ute, and rising through a bed of fine white sand, (which it keeps 
in constant agitation,) forms a very striking object. The water 
from the springs, after flowing a distance of fifteen rods over the 
bottoms, falls into a rocky channel worn out of the sand-rock, 
along which it rapidly descends for a couple of rods farther, where 
it enters the river, but not before it has received the water of an- 
other spring whose issue is from between the sandstone layers. 
Two miles after leaving the springs, the traveller is opposite the 
tragically famous Starved Rock.* It forms a part of the bluff on 
the south side of the Illinois, projecting promontory like, quite 
into the bed of the river, and rising twenty or thirty feet higher 
than the average level of the bluffs. Its face towards the river 
is perpendicular, and even overhanging. On some of the maps 
of the county its height has been stated at two hundred and fifty 
feet, which is certainly incorrect,—it having recently been meas- 
ured by Mr. O. W. Jerome, civil engineer of Rockwell, who finds 
ein one hundred and forty feet above the level of the Il- 
* About one Saale years since, a ferocious tribe of Indians, being driven by 
their enemies upon this projecting point of the Mlinois bluff, were reduced to 
submission by actual starvation. 
Vou. XXATV.—No. 1. 19 
