26 



PROCEEDINGS OF THE GEOLOGICAL SOCIE'ir. 



[Nov. 9, 



colour, and are encrusted by a calcareous cement, those of the lime- 

 stone being of the usual brown or grey tint, — the original heat of the 

 basaltic lavas having altered the degree of oxidation of the iron, con- 

 stituting the colouring-matter of the flint, by which the brown was 

 converted into a red. 



The White Limestone bears evidence of great denudation, firstly, 

 in its variable thickness, attaining a maximum of about 100 feet at 

 ^^Tiitehead and Cave Hill, and dwindling down to a few feet in Colin 

 Glen and Woodburn, and being even absent in the lower section in 

 the Woodburn River ; secondly, in the flint-gravel bed which is inter- 

 posed between it and the basalt, which is a constant accompanying 

 feature throughout the district. A fine exposure of the gravel is to 

 be seen in the White Limestone quarries at Kilcorig, near Lisbum, 

 as represented in the following section. 



Fig. 2. — Section at Kilcorig, Lishiirn. 



Thickness. 



1. Superficial drift, a stiiF clay with imbedded blocks of basalt 4 6 



2. Basalt, rudely columnar, attenuated on the eastern part of 



the section to q q 



3. Bituminous band, averaging 9 



4. Gravel -bed, composed of altered chalk-flints in an ochreous 



paste, fiUing up the hoUows of the denuded White Lime- 

 stone, and with an average thickness of 3 



5. White Limestone (Upper Chalk?) with numerous ft. in. 



layers of fiints and few fossils 21 6 



5'. ' Flinty flag,' a highly splintery limestone, irregu- 

 larly crowded with flints, its upper surface 

 covered with branching Sponge-remains im- 

 bedded in a glauconitic paste. Very fossihferous. 1 



5''. Two bands of hmestone separated by J 1 3 



a glauconitic layer 1 9 



White Limestone, with flints 13 



37 



6. Variegated marls of the Keiiper formation. 



