[ 70 ] 

 XI\'. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



June 6. — A PAPER was read containing Remarks on Sec- 

 ■^^ tions presented by the Rivers Isla, Melgum, Pro- 

 son, and S. Esk in the county of Forfar, with some general 

 Observations on the Geology of that County: accompanied 

 with Specimens ; by Charles Lyell, Esq. Sec. G.S. 



The county which formed the principal subject of this com- 

 munication is situated on the southern flank of the Grampians ; 

 it is occupied by old red sandstone, grauwacke and argilla- 

 ceous schist, with their associated porphj'ries. The strata are 

 clearly exposed by the rivers that cut through ihem. They 

 are very highly inclined, and dip for the most part towards 

 the south. The old red sandstone may be described as con- 

 sisting of two formations of sandstone, with a formation of 

 conglomerate of great thickness interposed between them. An 

 extensive formation of felspar porphyry occurs in the lower 

 part of the conglomerate; and it is from the broken and rolled 

 fragments of this porphyry that the conglomerate is for the most 

 part composed. Between the porphyry and the conglomerate 

 a rock prevails of a mixed character, which seems intermediate 

 between the two, and which it is difficult to describe or ac- 

 count for. The lower red sandstone which is beneath the 

 conglomerate is in many parts seen to be traversed by a mass 

 or dyke of greenstone, wliich passes into serpentine, in which 

 form it continues through a great part of its course; it lies 

 parallel with the strata. The lower red sandstone, which is 

 for the most part schistose and not of great thickness, alter- 

 nates with grauwacke at its juncture, and the grauwacke with 

 ai-gillaceous schist. A large mass of porpliyry, resembling that _ 

 of the Elvans of Cornwall, intersects in one ]iart of the district 

 the superior beds of the grauwacke formation. The paper 

 concludes with some observations on the primary locks of the 

 Grampians in the county of Forfar. 



June 20. — A Notice was read On some fossil Bones of an 

 Ichthyosaurus, from the Lias near Bi'istol ; also On two new 

 Species of Fossil Teeth : by George Cumberland, Esq. Hon. 

 Mem. G.S. 



A Letter was read, accompanying some Specimens from 

 Stonehenge, by Godfrey Higgins, Esq. 



An Extract of a Letter was read from Lieut. J. Short, R.E., 

 addressed to and conuunnicated by Dr. Babington, Pres. G.S., 

 containing some Remarks on the Lsle of Bourbon. — The 

 Isle of Bourbon, wliich is situated about 1 20 miles from the 



Mauritius. 



