LANCASTER COUNTY. 465 



CHAPTER XIII. 



GEOLOGY OF LANCASTER COUNTY. 



"For an extended view of the Geology of the county, we 

 ^lust refer to the final report of the general survey authorize(J. 

 ty the State government. 



In glancing over Mr. Scott's very beautiful and accurate map 

 of Lancaster county, it will be seen that the surface is broken 

 by irregular east and west ranges of hills, no one of which can 

 be properly styled a mountain. Commencing at the south, 

 we find an extensive formation of primary stratified, or meta- 

 morphic rocks, such as mica slate and talcose slate, the latter 

 having garnets imbedded in it. These are quite abundant on 

 the Susquehanna, below Pequea creek. Occasional patches 

 of limestone* and clay slate occur, and the latter is extensively 

 worked for roofing purposes, at a place called Slate-hill. — 

 Ascending the river, we find the same formation extending to 

 Turkey-hill, where it terminates, about two miles below the 

 village of Washington, or about the fortieth parallel of latitude. 



The next rock in ascending order, is a close grained, very 

 hard, siliceous sandstone, best seen at the mouth of the Chic- 

 quesalunga, between Columbia and Marietta, where it strikes 

 the Susquehanna in a bold blulT upwards of three hundred feet 

 in height. It is found at the opposite boundary of the county, 

 and extending into Berks, forms the hill on the south side of 

 Reading. A great deal of iron ore (argillaceous oxid and 

 hematite) has been taken from the clay overlying this forma- 

 tion, which although possessing some of the characters of the 

 preceding, such as large veins of quartz, and traces of fel- 

 spar and tourmalin, may probably be looked upon as the 

 lowest of the transition, rather than the uppermost of the pri- 

 mary stratified. This conclusion, however, could scarcely be 

 attained from an examination of the rock, limited to our own 

 localities. To understand it fully, it must be studied in tho 

 atate of New York. 



*Two miles below the mouth of the Concstoga, for example. 



