Geology. 275 



witli LWiothammon and Polytrema : this circumstance indicates 

 that this basalt was exposed upon the sea bottom in early IMiocene, 

 or perhaps pre-Miocene times. On the right hand of section A 

 on p. 272 this basalt is marked G, and is made to correspond to 

 the upper basalt overlying the limestone B in the rest of the 

 section ; this is perhaps a mistake, since it agrees very nearly 

 with the basalt F underlying that limestone, which, together with 

 the overlying basalt and ash beds, seems to be wanting on this 

 southern end of the cove. It may, however, be remarked that 

 the limestone A is very similar in character to B (IS^o. 522, p. 231), 

 and if it were not that its fossil contents (see ]^o. 2, p. 226) are 

 said to be rather different and point to a possibly somewhat greater 

 age, I should have regarded it as the southern continuation of B : 

 in that case the basalt would be correctly lettered. Indeed, 

 I believe this last interpretation to be correct. 



The upper yellow limestone (B) just referred to forms a prominent 

 cliff throughout about the middle two-thirds of the cove. At its 

 southern end it seems to have been cut out by the fault marked 

 Y-Y (rig. 2, A), but its termination is largely concealed by the 

 talus derived from the lofty cliffs of Miocene limestone (C). A little 

 farther to the north this cliff is again interrupted by another fault, 

 X-X (Fig. 2, A), the downthrow side of which is towards the north ; 

 this causes the limestone to terminate abruptly against basalt and 

 ash, and to reappear at a lower level, where it again forms a nearly 

 continuous cliff, low at first, but increasing in height towards the 

 north, where it sometimes reaches 60 feet. At its northern 

 extremity it becomes broken up into minor cliffs (P, Fig. 2, B) 

 separated by soil-clad slopes, beneath which it finally disappears. 

 The foot of the cliff is from 200 to 250 feet above the sea, but 

 except in one or two places where it rests on volcanic rocks (e.g. 

 at L and F), the base of this limestone is concealed beneath talus 

 which forms a steep rock-strewn slope to the shore platform. This 

 limestone is described on p. 231 as IS^o. 522; it is remarkable for 

 the absence of Orhitoides, which is found in the rocks both above 

 and below. The beds dip slightly seaward (at from 5° to 10°), 

 and are broken up by joint planes into great cubical masses, many 

 of which strew the platform below, of which, moreover, they 

 probably form the chief foundation ; blocks of the same limestone 

 also appear on the foreshore in the middle of the cove. 



As already mentioned, the base of this limestone is mostly 

 concealed beneath talus, but at a few points it can be seen to rest 

 upon volcanic rocks ; in all cases it seems to have been deposited 

 upon these rocks long after their consolidatioil, and near the junction 

 often contains fragments of them. Of these volcanic rocks there 

 are two series — an older, trachytic, and a later, basaltic. The chief 

 exposure of the former occurs near the middle of the cove (at L on 

 the right-hand side of section B in Fig. 2), where it forms a great 

 boss projecting into the overlying limestone. The extent of the 

 mass cannot be determined, since its borders are mostly concealed 



