*24 OBSERVATIONS ON THE GEOLOGY 



The limestone, grey icacke, and grey wacke slate, generally oc- 

 cupy the vallies; the quartzose aggregates, the ridges; amongst 

 which is that called the millstone grit; this must not be con- 

 founded with another rock, likewise denominated the millstone 

 grit, which is a small grained granite, with much quartz, found 

 in the. primitive formation; there are many and extensive caves 

 in the limestone of this formation, where the bones of many 

 animals are found, as well as the remains of marine insects and 

 shells. 



Beds of coal-blende, accompanied by alum slate and black chalk, 

 have been discovered in this formation on Rhode Island; the 

 Leheigh and Susquehannah rivers; (a large body of alum slate 

 which occurs on Jackson's river in Virginia is perhaps only a 

 part of a similar formation;) powerful veins of the sulphate of 

 barytcs cross it, in many places it is granular, as that near Fin- 

 Castle; or slaty, as in Buncomb county, North Carolina. 



Iron and lead have as yet been the principal metals found in 

 this formation; the lead in the form of galena, in clusters, or 

 what the Germans call stock-werck, as at the lead mines on New 

 river, Wythe county, Virginia; the iron is disseminated in the 

 form of pyrites; hematitic and magnetic iron ore*, and conside- 

 rable quantities of the sparry iron ore occur in beds and they are 

 likewise disseminated in the limestone. 



SECONDARY FORMATION. 



The south east limit of this extensive formation is bounded 

 by the irregular border of the transition, from between the Ala- 

 bama and Tombigby rivers, to the Catskill mountains. On the 

 north west side it follows the shore of the great lakes, and lo- 

 ses itself in the alluvial of the great bason of the Mississippi, oc- 

 cupying a surface from 200 to 500 miles in breadth. 



Its greatest elevation is on the south east boundary, from 

 which it falls down, almost imperceptibly, to the north west 

 and mingles with the alluvial of the Mississippi, having an out- 

 line of mountain, straight and regular, bounding Jong and pa- 

 rallel ranges of a gradually diminishing height as they approach 

 theN. W. limits. An almost horizontal stratification, orthestra- 



