On the Igneous Hocks of the South of the Isle of Man. 185 

 April 8.— Dr. W. T. Blanford, E.R.S., Vice-President, in the Chair. 

 The following commnnications were read : — 

 1. " The Cross Eell Inlier." By Prof. H. A. Nicholson, M.D., 

 D.Sc, E.G.S., and J. E. Marr, Esq., M.A., Sec.G.S. 



The tract of Lower-Palseozoic rocks lying between the Carboni- 

 ferous rocks of the Cross-Eell range and the New Red Sandstone 

 of the Eden Valley is about sixteen miles in length, and little more 

 than a mile in average breadth ; the Inlier extends in a general 

 N.N.W. and S.S.E. direction, and the normal strike of the rocks is 

 about N.W. and S.E. The tract is divided along its entire length 

 by a fault, which separates the Skiddaw Slates (with the Ellergill 

 Beds of one of the authors and the Milburn Series of Mr. Goodchild) 

 from higher beds on the west. A detailed classification of the 

 Skiddaw Slates is not attempted, but the authors describe the suc- 

 cession of the rocks in the faulted blocks of the western portion. 

 Their classification is as follows : — 



Coniston Grits = Ludlow. 



Coniston Elags (lower portion) = Wenlock. 



Stockdale Shales =Llandovery-Tarannon. 



Ashgill Shales. ") 



Staurocejjhalus Limestone. 



Dufton Shales and Keisley Limestone. )> ==Bala. 



Corona Beds. 



Rhyolitic Group. J 



A brief comparison of these rocks with those of other regions is 

 made by the authors. 



Two Appendices are added. One by Mr. Alfred Harker, M.A., 

 F.G.S., contains petrographical notices of certain sedimentary and 

 volcanic rocks in the Skiddaw Slates, of the volcanic rocks of the 

 Eycott and Rhyolitic groups, and of the principal varieties of 

 intrusive rocks. The second, by Mr. A. H. Eoord, E.G.S., contains 

 a description of some Cephalopods from the rocks of the Inlier. 



2. " On the Igneous Rocks of the South of the Isle of Man." 

 By Bernard Hobson, Esq., M.Sc, F.G.S. 



Omitting the Foxdale Granite, the oldest igneous rocks of the 

 island appear to be the diabase dykes of Langness &c, intrusive in 

 Lower-Silurian slates. The Crosby microgranite dyke is also 

 intrusive in these beds, and though its age is difficult to fix, 

 it is probably newer than the Eoxdale Granite, which appears to be 

 of post-Lower Silurian and pre-Carboniferous age. 



Next come the volcanic rocks of Lower-Carboniferous age — an 

 augite-porphyrite series consisting of tuff, breccia, agglomerate, 

 bedded lava, and intrusive masses exposed in a narrow strip 

 extending from Poolvash to Scarlet Point. A vent seems to 

 have been opened during or after the deposition of the Poolvash 

 limestone, from which fine volcanic ashes were ejected to form 

 marine tuff. At intervals between the eruptions the Poolvash 

 marble was deposited, and became interstratified with the tuff. 

 The vent then probably became plugged up, and a violent explosion 



