DEPOSITS AND ELEVATION. 9 



hole or pocket of the Limestone rock. There the bouldcr- 

 clay has been traced overlying the deposit. No fossils have 

 occurred to mark its age ; but it has the appearance of being 

 in situ, and of having probably been deposited after the 

 limestone had taken its present form. 



It has been fully described by a good geologist^ Mr. 

 Maw (Geol. Mag. ii., 1865), from whose account the fore- 

 going description is abridged. 



Another, but less important, patch of the same deposit 

 may be traced in a very similar position, namely, higher 

 up the larger valley of the ^' Old road.^^ Mr. Maw did 

 not find chert bands on Little Orme^s Head ; nor have I 

 been able to detect any in the limestone of the larger hill ; 

 but there are traces of a cherty stratum amongst the grit- 

 stone rocks which form the east end of the Telegraph -hill 

 ridge. 



ii. The next of the deposits are glacial and boulder- clays 

 of a late age. These appear in four distinguishable forms. 



a. "Probably the oldest of these is that described by Mr. 

 Bonney as a bed of tenacious dark-blue clay, full of small 

 pebbles of a dark slaty rock, rising i or 2 feet at the foot 

 of the western cliff of the isthmus, and traceable for some 

 distance below high-water mark. It may be that this and 

 the following bed {b) are the same, seen under somewhat 

 different conditions. 



A not dissimilar bed is well seen in the sections of the 

 railway-cuttings near Bangor Station. That bed occurs 

 in two strata, one full of small stones and coarse sand, and 

 the other, an upper layer, with more clay and finer sand, 

 and containing a few fragments of shell too small and too 

 much worn to be determinable. It is, however, at a con- 

 siderable elevation above the sea-level, and is not overlain 

 by any boulder- clay. 



b. A close, greyish, olive-coloured, rather sandy bed, 

 with rounded stones of various rocks, comes up on the beach. 



