CARADOC SANDSTONE- — INLAND COURSES OF. 



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System, which rises in thick stratified masses both near the western extremity of the mainland, and 

 specially in succeeding lower shelves in the adjacent island of Skomer. (See Vignette, head of this 

 chapter, and PL 35. f. 10.) These rocks, however, are associated with much trap, which is some- 

 times arranged parallel to the strata, and at other times intrusive ; but of these we shall speak here- 

 after. Having described those parts of the coast at which the Silurian formations are exposed, I 

 may now recall attention to those tracts where the lower rocks of the system appear in the interior 

 of the county. 



Caradoc Sandstone — inland course. Orlanton and Hoten Band. 



This is a narrow band of Lower Silurian Rocks, less than half a mile in its greatest width, which 

 has been heaved through the Old Red Sandstone for upwards of three miles, from Orlanton on the 

 west, to the upper end of Spread Eagle Pill on the east. At Mallock Slate Mill, the beds are rotten 

 argillaceous sandstone, nearly vertical, containing Leptcena sericea, &c. At Hoten they are asso- 

 ciated with hard quartzose grits, plunging 45° south, and the band subsides beneath the Old Red 

 Sandstone in a point near Spread Eagle Pill. They are, however, for the most part, perishable, 

 shelly sandstones, with imperfect slaty cleavage, and contain among other fossils the well-known 

 Orthis bilobata, so abundant in all the rocks of this age from Shropshire and Montgomeryshire, to 

 the south-western extremity of this county. 



Johnston Band. 



Another insulated band of Caradoc sandstone, double the length and width of that of Hoten, 

 extends also from west to east to the south of Johnston, reaching from Romans Castle on the west 

 (where it is penetrated by trap rock) to a point near Dumpledale, between Rosemarket and Langam. 

 In the eastern part of its course this band is flanked on each side by ridges of trap, but on the whole 

 of its southern border, ranging by Tearson, Redstock, Harmeston,.and Hayston Mill, and also at its 

 north-eastern extremity, for a short space at Dumpledale, it is in contact with Old Red Sandstone. 

 In this band, among numberless impressions of encrinites and the fossils previously mentioned, I 

 found the Pentamerus Icevis, so characteristic of the upper portion of the Caradoc sandstone. The 

 prevailing inclination of these beds is to the south, but in the narrow zone, between the two ridges 

 of trap south of the Trooper's End, they are thrown in discordant directions, as seen in two small 

 combs above Nash Mill. 



Haverfordwest Band. 



The Caradoc sandstone is fully and clearly displayed in the cliffs on both banks of the river at 

 Haverfordwest, where it sometimes runs in vertical strata from east to west, and supports the 

 greater portion of the town, while in the western and southern suburbs it constitutes arched 

 promontories, one of which runs out with a south-westerly strike to the Maudlin Bridge, where, 

 dipping to the south-east, it abuts against the millstone grit of Poorfield. The rock is composed 

 of imperfect, argillaceous flagstone, with much shivery schist, passing occasionally into concretionary 

 masses. Courses of solid stone are rare, the most persistent masses ranging from the castle 

 of Haverford on the east to Sutton on the west. Among the fossils I observed Orthis bilobata, 

 O. grandis, Terebratula lacunosa (Schloth.), &c. 



