94 PEOCEEDZN'GS OF THE GEOLOGICAL SOCIETY. 



of these striae having been produced by landslips or local disturbance. 

 A quarry on the same horizon, near itochdale, exhibits similar phe- 

 nomena. As collateral evidence of ice-action, he alluded to the 

 boulders frequently found in the coal-seams. 



Discussiojf. 



Dr. HxsDE considered that the markings on one of the specimens 

 exhibited more nearly resembled slickensides than striae produced by 

 ice-action. 



Mr. ToPLET said the question of the striae Tras difficult to decide ; 

 but he thought the reference to boulders in a coal-seam a thousand 

 feet above did not help matters. He considered the appearances 

 due most probably to movement of the natui^e of slickensides. It 

 was too hazardous to put it down to ice-action. 



4. " The Greensand Bed at the base of the Thanet Sand." By 

 Miss Margaret I. Gardiner, Bathurst Student, Xewnham College, 

 Cambridge. (Communicated by J. J. H. Teall, Esq., M.A., P.G.S.) 



5. "On the Occurrence of ElepJms meridionalis at Dewlish, 

 Dorset." By the Eev. 0. Pisher, M.A., P.G.S. 



6. " On Perhtic Pelsites, probably of Archasan Age, from the 

 flanks of the Herefordshire Beacon, and on the possible Origin of 

 some Epidosites." By Prank Ptutley, Esq., P.G.S. 



7. " The Ejected Blocks of Monte Somma.— Part 1. Stratified 

 Limestones." By H. J. Johnston-Lavis, M.D., P.G.S. 



[Abstract.] 



Introductory. — The Author referred to the Hamilton collection, 

 now in the British Museum, and to the work of Prof. Scacchi, who 

 enumerates 52 mineral species as having been found in the ejected 

 blocks, and indicated the importance of these from a geological and 

 volcanological point of view. His own collection contains over 

 600 specimens, showing the gradation from unaltered limestones, 

 through various stages of change into numerous varieties of " true 

 metamorphic rocks," which, in their turn, shade into igneous rocks 

 more and more approaching the several modifications of the normal 

 cooled magma of the volcano. Moreover, such rocks come from 

 depths where they have not been affected by alterations of a 

 secondary nature. 



He then gave a classification of the varieties of ejected blocks. 

 The Tertiary rocks are but slightly metamorphosed, while the lime- 

 stones of Cretaceous or earlier age afford an almost unlimited series 

 of mineral aggregates. Physical changes have converted them into 

 carbonaceous and saccharoidal marbles ; next oxides and aluminates 

 Jiave separated, and silicates ha-se been introduced. Such rocks 



