194 GEOLOGY OF ILLINOIS. 



The True Drift, in the western part of the county, consists, mainly, of the 

 tough blue " boulder clay," with pebbles and boulders, sometimes also including 

 fragments of wood, overlaid but slightly, or not at all, with gravel, and under- 

 laid, so far as known, with a bed of " hard-pan," and a water-bearing quick- 

 sand which has thus far prevented any knowledge of the underlying materials. 

 The eastern part of the county, on the contrary, shows but little boulder-clay, 

 this being replaced by a heavy layer of sand and gravel. Township 34 north, 

 range 6 east, has no known outcrop of rock, and wells near its south line have 

 reached depths of forty-eight, fifty and fifty-two feet, before meeting the quick- 

 sand. Townships 31 and 32, of the same range, and so much of 33 as lies 

 south of the river, together with townships 31 and 32, range 7 east, possess no 

 outcrop of rock, but the depth of the Drift is not known. At Gardner, in sec- 

 tion 9, township 31 north, range 8 east, the Drift is said to be one hundred 

 feet deep at the coal shaft. At Braceville, section 25, township 32 north, 

 range 8 east, it was found to be forty-four feet deep. Going northward into 

 townships 33, in ranges 7 and 8, it rapidly thins out, owing partly to the down- 

 ward slope of the surface, partly to the upward slope of the surface of the un- 

 derlying rocks, which come to the surface in the northern part of these town- 

 ships. Much of the " coal land " in the immediate neighborhood of Morris is 

 bare of drift, having been stripped by the old river. To the northward, how- 

 ever, through township 34 north, range 7 east, the gravel and boulder-clay lie, 

 in some places, forty feet deep. Township 34 north, range 8 east, is deeply 

 buried in Drift; at Minooka, on the line between sections 1 and 2, a well- 

 boring found one hundred feet of gravel overlying the shaly limestone of the 

 Cincinnati group. 



Rock Formations. 



Coal Measures. The beds of the Coal Measures occupy far the larger part 

 of the surface of the county. The outcrops, however, are so disconnected, and 

 the beds so irregular, that I have been unable to construct any general section 

 to represent connectedly all the outcrops. Apparently, the higher beds ex- 

 posed in the county are those which outcrop near the old coal openings on the 

 Waupecan, in the southeast quarter of section 20, township 33 north, range 7 

 east. I was unable to find any outcrop of beds above the coal, and did not 

 learn whether any were seen in the deeper parts of the mine. Near the out- 

 crop, a foot of coal was left as a working roof. The seam is five feet thick, 

 resting on a bed of fire clay. It is coal No. 4, of the Illinois valley section. 

 The connection below is not exposed, but, at a short distance from the floor of 

 the seam, not over ten feet, we came upon a coarse, ferruginous, shaly sand- 

 stone, filled with fragments of Lepidodendron, Calamites, Neuropteris hirsuta, 

 etc., with an occasional streak of coaly matter. Of this bed, there is a low, 



