LEE COUNTY. 131 



and on to Lamoille in Bureau county. At Lee Center, in a grove of tim- 

 ber south-east of the village, tbere is a good exposure, where abundance 

 of fine building stone is quarried. The stone is somewhat thin-bedded 

 here. At Sublette, or its vicinity, there is another quarried exposure, 

 and in north-eastern Bureau county, if I mistake not, some low out- 

 crops exist. The Galena limestone also comes in from Ogle county in 

 the north-east corner of Lee, and underlays two or three townships there, 

 extending down perhaps to the head waters of Spring creek and the 

 Inlet marshes. It is almost impossible to trace or bound the uuderlay- 

 ing rocky formations in the level prairies of central and southern Lee 

 county : but I feel quite sure the Galena limestone extends back for a 

 considerable distance on either side of the anti-clinal axis above referred 

 to, and so continues until it runs under the coal fields of Bureau county, 

 or thins out and disappears from among the underlaying rocks. 



An extended lithological description of this rock is hardly necessary 

 in this place. It has been many times described in the reports of our 

 Western geologists, and also in my reports upon Carroll, Stephenson 

 and other counties in the northwestern part of the State. As developed 

 in Lee county it is more massive and solid than in some localities fur- 

 ther north, belonging as it does to the lower part of the formation. It 

 has that rich, warm, cream color so characteristic of this stone. 



The many economical uses to which this rock is put ; its great thick- 

 ness and local development, being only found in the lead basin of the 

 Northwest : the rich stores of galena contained in its crevices and re- 

 sulting clays, and the geological questions and phenomena suggested 

 by an examination into its deposition and the origin of its metalic 

 wealth, will always make it a very interesting member in the series of 

 Illinois rocks. Neither is it devoid of organic remains, as will be seen 

 when I come to notice the fossils characteristic of these J-ee county for- 

 mations. The casts of fossils therein entombed are of more than usual 

 interest. 



The Cincinnati Group. No regular outcrops of this formation, I 

 think, exist in the county. I have intimated, in speaking of the Ga- 

 lena limestone, that nearly all that part of the county north and west of 

 Rock river is underlaid by that formation. This is not fully correct. 

 Linn Grove, near Rock river, and almost on the western line of the 

 county, and a small strip of laud surrounding it, has a thin deposit of 

 the peculiar shales and clays of this group underlaying the superficial 

 deposits, and overlaying the Galena rocks. The materials excavated 

 from wells in that vicinity show this. 



In one other locality north of Rock river I suspect the existence of 

 this formation. The base of " The Mounds," about two miles north and 

 a little west of the west end of Sugar Grove, is composed, I think, of 



