LEE COUNTY. 129 



city limits of that city the bluffs are mostly composed of this rock. Exten- 

 sive quarries and lime kilns are seen at many places in this distance. The 

 greatest thickness developed along these quarries is from sixty to seventy- 

 tive feet. The small ravines leading down through the hill, show this 

 rock in their channels, sometimes, for several miles. In these localities 

 it resembles the white Hamilton limestone about Rock Island. North 

 of Hock river its area is more circumscribed. Following up Franklin 

 creek this rock soon shows itself in the hill-sides, even before the St. 

 Peter's sandstone has disappeared below the surface. In one instance 

 a detached sort of a tower rock stands in the valley of the small stream, 

 entirely disconnected with the hills on either side. All the way up the 

 rocky exposures may be seen. Near the village of Franklin, where the 

 Dixon air line division of the North-western railroad crosses that stream, 

 a series of large quarries, extensively worked in past years, line both 

 sides of the creek banks for a considerable distance. A large hotel and 

 other buildings in the village were constructed with the material taken 

 from these quarries. Franklin grove, a fair sized body of timber, is un- 

 derlaid by these beds, which outcrop in the creek. A section of Frank- 

 lin creek would show the overlaying drift clays of varied thickness ; 

 about forty feet of this Blue limestone ; and about twenty-five feet of 

 the St. Peter's sandstone. These localities, and a few others in this part 

 of the county, are the only places in the county where natural out- 

 crops of the Blue or lower Trenton may be seen. In the south and 

 south-western part of the county this rock may exist to a limited extent, 

 but there are no natural outcrops, and it is hard to tell what forma- 

 tions lay under these level prairies. 



Where best developed in Lee county, the Trenton limestone at the 

 top of the quarries is thin-bedded, broken up, and of a light buff color. 

 Towards the bottom the layers become heavier, intersected occasion- 

 ally with upright clay seams ; and in the bottom several massive layers 

 of blue stone are found. On fresh fractures the color is a dark -blue ; 

 but it soon weathers to a bright sky-blue. 



Some of the layers are full of fossils, the remains of organic life. 

 When highly polished, these make a handsome marble, covered with 

 the delicate tracings of the imbedded fossils and casts. 



In many instances I noticed the "pot holes" spoken of by Dr. EVERETT, 

 over the high surface of the country underlaid by this rock. They are a 

 characteristic feature in the face of the country east of Dixon, and excite 

 the curosity of the most superficial observer. 



The Galena Limestone. I prefer to retain this name in speaking of 

 this member of the Trenton limestone. Descending Eock river from the 

 locality of the Blue limestone quarries above Dixon, the Galena lime- 

 stone is first noticed on the south side of the river, in the fine outcrop 



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