410 PROCEEDlJ^GS OF THE GEOLOGICAL SOCIETY. [June 16, 



The east side of the glen consists below of mica-slate, followed higher 

 up by a dark red, line-grained sandstone, on which rest enormous 

 masses of coarse conglomerate, sometimes from 100 to 150 feet thick, 

 and cropping out along the whole escarpment of the mountain. In many- 

 places the two formations may be traced within a few feet of each other ; 

 but no distinct instance of an actual junction was observed. The nature 

 of the conglomerate, as often happens, rendered it impossible to ascer- 

 tain its dip with accuracy, and there is so much false-bedding in the 

 sandstones, both those underlying, and those occasionally included in, 

 the conglomerate, that they did not afford much assistance in deter- 

 mining the position of the mass. So far, however, as could be ascer- 

 tained, there is a remarkable coincidence between the dip of the mica- 

 slate and that of the sandstone resting on it, where both are seen in 

 the closest proximity. The inclination of both masses is to the east 

 or south-east, and occasionally the amount of the dip did not differ 

 above a few degrees, its direction in both rocks being to S. 7^° E. by 

 compass. A similar approximation in the position of these formations 

 is seen on the north side of the Bay near Braskomil. In this place 

 the mean of fourteen observations on the inferior mica-slate gave a dip 

 of 41^° to S. 58° E., and of eight observations on the red sandstone, 

 of 49° to S. 63|° E., — a closer approximation than is found in separate 

 observations on the same rock. The coincidence is also more remark- 

 able from a mass of greenstone, fifty yards wide, having intruded al- 

 most at the junction of the two formations, only one bed of mica-slate, 

 hardened and bent over the curved surface of the trap, being seen 

 above it, dipping at 45° to S. 65° E., or within a few degrees of the 

 mean of the sandstone resting on it. In the hill to the north several 

 smaller patches of conglomerate and red shale are seen in a similar 

 approximate parallelism to the mica-slate and limestone in their 

 vicinity. 



In examining my notes I was surprised to find a similar coincidence 

 in the dip of these two formations in the extreme south of the penin- 

 sula near Keills. The mica-slate, as formerly stated, dips in this place 

 to S. 55° E., and the same direction was found in the red sandstone 

 and conglomerate which abuts on the shore in fine bold sea-worn cliffs 

 near the old grave-yard of Kilcolmkill. A low alluvial tract, how- 

 ever, divides the formations in this place, and I had no opportunity 

 afterwards of examining the locality more closely. 



Although these observations are perhaps not sufficient to prove that 

 the red sandstone and conglomerate were deposited conformably on the 

 horizontal mica-slate, they at least show a closer coincidence than I 

 have observed in other parts of Scotland. When we contrast them 

 also with the very marked unconformability of the Devonian red 

 sandstones to the Silurian greywackes in the south of Scotland, they 

 may be regarded as indicating that the elevation of this portion of the 

 crystalline strata is not of very ancient date. 



The same conclusion may be drawn from a consideration of the mi- 

 neral character of these conglomerates, which in other respects also is 

 very remarkable. The materials composing them vary in size from 

 fine sand to rounded blocks frequently of six or eight inches, and not 



