330 



beds of copper slates. In volume VIII of the Journal of 

 the Dublin Geological Society, page 86, the gray copper 

 ores, which characterize the red slates at the base of the so- 

 called Carboniferous formation in the North and South of 

 Ireland, are said to lie two thousand six hundred and forty 

 feet below the base of the carboniferous limestone. Whether 

 these rocks be Devonian or Carboniferous has been discussed 

 by Mr. Jukes and Dr. Griffith, and decided by the latter, with 

 the concurrence of Prof. Haughton and other British geolo- 

 gists, in favor of their classification as Carboniferous, on the 

 ground of their containing fossils of that type. 



It is remarkable that, along the base of the Alleghany 

 Mountains, where our Pennsylvanian sub-carboniferous forma- 

 tions X and XI, so immensely thick at Pottsville, have thinned 

 away to a few hundred feet, — and also in northeastern Penn- 

 sylvania, Avhere the three formations IX, X, XI, are all together 

 reduced to a thickness of not much more than two thousand 

 feet, bringing the undeniably Devonian formation VIII, up to 

 within that distance of the coal, there occurs a copper-ore 

 slate horizon a few feet thick, which will exactly correspond 

 in position to the copper-slates of Ireland. 



The Society was then adjourned. 



Stated Meeting, May 18, 1860. 

 Present, fifteen members. 

 Dr. Wood, President, in the Chair. 

 The following donations for the Library were announced : — 



Annalcs dcs 3Iines, Vol. XV, 3d part, and Vol. XVI, 4th pt. of 1859. 



Intorno alia influenza dell 'Elettrico nolle formazione della Granuola, 

 &c. An Svo. pamphlet memoir of Prof. Zantcdcschi. 



American Journal of Science for May, 18G0. 



Journal of the Franklin Institute for May, 1860. 



Centennial Anniversary of the Foundation of the Germantown Aca- 

 demy, 1860. 8vo. pamphlet, 58 pages. Philadelphia. 



