Geology of North Carolina. 



1.1 J 



19. Breccia — consists of rolled pebbles imbedded in a fer- 

 ruginous greenstone ; (Is not this the trap conglomerate of 

 Macculloch ?) or in argillite, imbedded in the slate. (Is not 

 this gray wacke ?) 20. Serpentine — dark green, pale green, 

 iron black. 21. Clays and Ochres — pipe clay, potter's clay, 

 saponaceous, porcelain, red and yellow ochres. 22. Iron — 

 specular, oxide, magnetic, pyrites, native, brown hematite, 

 argillaceous, sulphate. 23. Manganese — black oxide, fer- 

 ruginous oxide. 24. Copper — red oxide, green carbonate, 

 pyritous. 25. Arsenic — arsenical pyrites. 26. Gold — in 

 veins, stream gold. 



From a suite of specimens from this formation, obligingly 

 sent to us by Prof. Olmsted, we should be disposed to add to 

 the above list, talcose slate and graywacke slate. It is well 

 known, however, that the characters of these rocks, are not 

 a little dubious. 



We approve of the caution of Prof. Olmsted, in denomi- 

 nating this series of rocks the slate formation, rather than the 

 transition formation. For he thus makes us acquainted with 

 the rocks themselves, as they exist in the arrangement of na- 

 ture ; which is of far more importance than to ascertain 

 where they should be placed in the system of Werner. 



Some of the members of this slate formation deserve 

 more particular notice. 



It is in this formation alone that gold is found in veins, al- 

 though the stream gold has been carried to some extent over 

 other roeks. According to Mr. Rothe, in No. 2, of the last 

 volume of this Journal, the veins of gold are found exclu- 

 sively in the greenstone. As, however, the mode of its oc- 

 currence and every important circumstance relating to it, 

 have been so well described, both in the memoir of Mr. 

 Rothe just alluded to, and in another by Prof. Olmsted in a 

 former number of this Journal, it is unnecessary, in this 

 place, to enter into details. 



Some of the porphyry of this slate formation is very fine 

 and well characterized. It occurs in beds and huge bowl- 

 ders.* 



* Cleopatra's Needles are stated in the Report, p. 26, to consist of porphyry. 

 We have not examined the subject ; but happen to have a specimen of well 

 characterized sienitic granite, broken from Pompey^s Pillar, by the missionary 

 Fiske, with the following label attached, in his own hand writing. " From 

 Pompey's Pillar, at Alexandria. Cleopatra's Needles are of the same kind of 

 stone." 



