THE CARBONIFEROUS LIMESTONE OF SOUTH-WEST GOWER 43 
of the Peninsula extends in bold rugged cliffs, forming 
some of the grandest coast scenery in Wales. 
Two small ranges of low rounded hills, of Old Red Sand- 
stone formation, cut off the limestone of the southern area 
of Gower from the rather more extensive mass lying to the 
northward. No good sections are to be found inland, nor 
have we present in the cliffs any such continuous section 
as is afforded by the Avon Gorge ; save some of the top 
beds, however, which have been removed by denudation, 
almost the entire series from Millstone Grit to Old Red 
Sandstone can be made out by following the coast line, 
where a series of curves and faults brings bed after bed 
into view. 
At Oxwich Bay a series of black shales occur, with vast 
colonies of Lithostrotion ; one of these shale beds ic seen 
on the cliff, but the greater part are buried under a huge 
sand-bank, and can only be seen in fragments at very low 
tide. The whole cliff from Oxwich round the headland to 
Porteynon is so dislocated and shattered by faults that it 
would be tedious and misleading to attempt to trace out 
the various horizons in this locality. At Porteynon Bay, 
however, a vast synclinal curve occurs in the beds, the top 
of the curve being occupied by Dolomitic Conglomerate ( 1 ) 
of Triassic Age, the original thickness of which cannot be 
stated, as the bulk of it has been eroded. This conglo- 
merate rests unconformably on the Carboniferous Lime- 
stone series, which had undergone, extensive denudation 
before the Triassic deposits were laid down. 
The successive zones may now be referred to in order, 
the notation adopted being that of Dr. Vaughan for the 
Avon Section. 
DIBUNOPHYLLUM ZONE. 
Sub-zone D 2 . 
The highest beds of the Dihunophyllum zone, that are 
