Mr. De la Beche on the Geology of Southern Pembrokeshire. 13 



of the Ridgevvay a loose conglomerate, consisting of rounded pieces of sand- 

 stone cemented together by soft red marl. This is particularly observable 

 on the road near the top of the hill above HoUoways, between Penally and 

 Tenby. 



The dip of the sandstone, in the westernmost of the two above-mentioned 

 peninsulas, at the cliffs north of the Angle Valley, is to the south, at an angle 

 of from 70° lo 80° : at the Cliffs near Patterchurch, in the same direction, at 

 about 40° ; and at East Pennar, near Pembroke, it is also to the south, at an 

 angle of about 80°. Owing to the want of natural sections, it is difficult to de- 

 termine the dip in the Ridgeway. To judge from the edges of a few beds by 

 the road-side between the Ridgeway and Carew, the strata are nearly ver- 

 tical. On the top of the hill above Penally, a few beds project above the soil^ 

 dipping at about 40° to the northward; but the eastern extremity of the Ridge- 

 way is almost wholly concealed by the sands of Penally Burrows. 



Orielton Subdivision. 



This subdivision, like that of Pembroke, consists of a band of old red sand- 

 stone running from west to east, and dipping on either side beneath carbo- 

 niferous limestone. For its precise limits I must beg to refer to the map. 

 Quartzose conglomerates are observed about Dry Burrows, near Orielton, and 

 between Lambeth and Lambeth Mill. 



At the westernmost point of this band of sandstone, in the cliff to the south 

 of West Angle, the strata dip to the north at from 70° to 80° : at Quaits Mill, 

 near Pembroke, they dip to the north-by-east at nearly the same angle. At 

 the easternmost point of the sandstone, in a sm;-,ll cove between ShrinkleFarm 

 and Old Castle Head, the sandstone is perpendicular, and continues so round 

 that head, and round Manorbeer and Swanslake Bays. The edges of the 

 vertical beds are beautifully displayed at low water in Manorbeer Bay. The 

 southern half of Caldy Island is the continuation of the sandstone of Old Castle 

 Head, and, like that head, has its beds vertical, and some of them of a light 

 greenish-blue colour mixed with those which are red. The direction of all 

 these vertical beds is from west-by-north to east-by-south. To the north of 

 Stackpoole Quay the beds are nearly vertical. 



§ 4. — Carboniferous Limestone. 



Like the greywacke and the old red sandstone, the limestone may be re- 

 ferred to two principal districts, the one lying to the north, the other to the 

 south of the Coal-basin. 



