ROCKS OF PEMBROKESHIRE. ‘525 
this coast. The latter, however, occur only at Pen-pleidiau Point, 
between Caerbwdy and Caerfai, where they are tolerably fossiliferous. 
In a cliff-section immediately to the 8.E. of Nun’s Chapel, the Cam- 
brian conglomerates may be seen resting unconformably on the edges 
of the Pebidian rocks, as is shown in figs. land 2. This section was 
Fig. 2.—Section showing Cambrian Conglomerate resting on edge of 
Pebidian beds in Cliff S.E. of Nun’s Chapel. 
2. Greenish sandstones. B. Pebidian. 
Cambrian { 1. Basal conglomerate. F. Fault. 
referred to by me in a previous paper as proving marked unconformity 
in this area between Cambrian and Pebidian. Dr. Geikie, however, 
has endeavoured to explain away this appearance by calling it a case of 
“ contemporaneous erosion accompanying Cambrian conglomerates””*. 
Evidently, on his theory of conformable succession, this was a very 
awkward case to deal with, and the only alternative was to call it one 
of contemporaneous erosion. This section and some adjoining ones, 
when examined with care, clearly show, however, thatit is utterly 
impossible to explain away the facts on any such hypothesis. Itisa 
curious fact also that this section is stated in the explanatory text of 
his paper, and in that accompanying the figure itself, to be in Caerfai, 
whilst it is in reality more than half a mile west of that creek, and in 
Nun’s Chapel Bay. The section,as given in his paper at p. 287, also is 
clearly an imperfect representation of the conditions exhibited, though 
the unconformity can be recognized even there. Though some of the 
conglomerates have been dropped by a fault in this section, it is 
fortunate that it has only taken the upper beds, and has left the lower 
ones, where they rest on the Pebidian beds, undisturbed. The 
thickness lost by the fault has not been great, as the majority of the 
green sandstones forming the next series are present in the section 
in a nearly vertical position. 
* Quart. Journ. Geol. Soc. vol. xxxix. p. 287. 
OsaG.o. No. 159: Qn 
