part 1] OX THE GEOLOGY OF THE OLD RADNOB DISTRICT. 15 



exposed in the extensive workings on both sides of the railway, 

 close to Dolyhir Station. Its original thickness cannot now be 

 determined, as the beds are nowhere seen in their natural relation 

 to the succeeding formations ; while the surface, at present exposed 

 to view, has evidently undergone extensive denudation. 1 The 

 actual thickness of the beds still remaining in the district is also 

 difficult to ascertain, because of the crushing and dislocation to 

 which they have been subjected, and this difficulty is further 

 increased by the general absence of stratification in the mass of 

 the limestone above the basement-beds. The un stratified character 

 of the limestone is probably due primarily to the mode of origin of 

 the deposit ; but any stratification which originally existed would 

 now be largely obliterated by the general crushing and recrystal- 

 lization which the rock has undergone. In the large quarry on 

 Yat Hill and in the old quarry east of it, the beds, apart from the 

 actual lines of thrusting, appear to lie generally in a more or less 

 horizontal position. This horizontal disposition of the beds can 

 be seen in the lowest beds of the limestone in the old quarry 

 ■occupied by the railway siding, and again on the south side of 

 the line in the downthrow portion of Dolyhir Quarry, already 

 mentioned. In Strinds Quarry, however, the bedding has been 

 almost entirely obliterated by the numerous planes of crushing 

 which here traverse the limestone. Elsewhere, the beds dip usually 

 at moderate angles in the neighbourhood of the dominant north - 

 and-south faults. In the old quarries at the northern end of 

 Yat Wood, the stratification is less obscured, and the beds show a 

 fairly uniform dip of 15° north-westwards. Combining these 

 different observations, we shall not be far wrong if we assign to 

 the deposit a thickness of about 80 feet, and estimate the original 

 minimum thickness at 100 feet. This agrees closely with the 

 ■section of the limestone exposed at Nash Scar (where, however, 

 the upper beds have been mostly quarried away) : it is greatly in 

 excess of the normal thickness of the Woolhope Limestone near 

 Presteign and elsewhere, and in itself indicates that the Dolyhir 

 and Nash-Scar Limestones were accumulated under somewhat 

 special conditions. The alteration of the deposit by igneous 

 intrusions, as postulated by Murchison, however intense, could not 

 account for this remarkable increase in thickness. 



The typical rock is a bluish-grey crystalline limestone, locally 

 iron-stained, but weathering to a pale grey or even white. It is 

 remarkably pure and, apart from one thin bed of shale, is free from 

 argillaceous matter. 



According to local records, the limestone has been worked for 

 some 300 years : on account of its purity, the rock is found to 

 be admirably suited for a flux in iron-smelting, and also as a gas- 

 purifier and for general agricultural purposes. 



1 The small patch of Wenlock Shale (PI. V, fig. 1) seen on the south side 

 of Dolyhir Quarry, let down by the fault already mentioned, may perhaps lie 

 conformably on the limestone, but its position close up against the fault 

 makes its relationship to the limestone difficult to ascertain. 



