TRANSACTIONS OF THE SECTIONS. 99 



grained and of the usual deep red colour, dipping S.E. at an angle of about 45°; 

 and starting from this point the griidually altered character of the rock becomes 

 apparent every few yards as we proceed towards the junction. 



The first appearance of change is shown in a series of chocolate-coloured rocks 

 with greenish veins and streaks traversing them ; and as these become more indu- 

 rated they turn lighter in colour, and take on a beautifully mottled appearance, 

 closely resembling variegated marble, and finally, within a few yards of the junc- 

 tion, the rock turns dark grey or almost black. The actual contact is beautifully 

 seen on the almost perpendicular face of the rock, under a waterfall formed by the 

 small burn Howing over the lip of the Come south of the grand peak of Ciod-na- 

 oigh. 



Identically the same appearances are observed when ascending up to the granite 

 in the bed of the " White Water," the falls of which form a conspicuous landmark 

 on the hillside above Oorrie. 



The author made these two points typical, and his specimens and diagrams re- 

 ferred to them ; but numerous other sections are laid bare in the small bums and 

 ravines intersecting tlie hillside, and bear out the same conclusions. 



The author showed a diagram from Oon'ie to the White Water, showing that if 

 it were not for the extensive denudation that has taken place we shoidd probably 

 see the Carboniferous rocks abutting against the granite, as they must originally 

 have done. lie also gave an enlarged copy of Dr. Bryce's map of the localities 

 referred to, accompanied by a dtiplicate map of the same localities and on the same 

 scale, with the supposed slate replaced by the Old Red Sandstone. In Glen Sannox 

 burn the junction appears to take place by contact of the granite with the ma.ssive 

 Old Red conglomerate, and he was able to exhibit specimens quarried out of the 

 bed of the burn showing large rounded quartz pebbles in a state of semifusion and 

 the matrix of the rock traversed by alternate black bands and streaks and white 

 seuiigrauitic veins and patches; but though the actual junction must be within a 

 few yards of the spot where he quarried, he was unable to lay it bare, owing to the 

 deep water and the mass of gravel and sand in the bed of the burn. 



lie also mentioned that everywhere at the point of contact with the Old Red 

 Sandstone the granite is delicately mottled or clouded (as shown by his polished 

 specimens), as if the black tilui of the absorbed mass had remained floating and 

 become lixed in the white pasty mass. And this appearance he holds is in itself 

 sulhcient to point to a junction of granite with rock other than slate ; for though 

 innumerable instances may be seen in other parts of the island of junctions of 

 granite witli true slate, in not a single instance is the adjoining granite atl'ected 

 in this particular manner. 



On Siliceous Sponges from the Carboniferous Limestone near Qlasgow. 

 By John Young, F.G.S. 



The author exhibited a series of mounted specimens of sponge-spicula re- 

 cently obtained from a deposit of rotted limestone filling fissures in the Carbo- 

 niferous Limestone series at Cunningham Bedlaud, near Dairy, Ayrshire. He 

 stated that the discovery of the spicules was due to the investigation of the 

 deposit by Mr. John Smith, of the Geological Society ot Glasgow. lie was not 

 aware of similar sponge-spicules having been found in any other Carboniferous 

 Limestcme district within the British Isles, and their abundant occurrence in this 

 deposit testified to the e.\istence of sponges witli large siliceous spicula over this 

 tract of the Scottish Carboniferous sea-bottom. 



