NORTH-WEST REGION OF CHARNWOOD EOREST. 87 



case more than 2 feet. A rude cleavage affects tlie fragments as 

 well as the matrix, dipping approximately at about G0° to a point 

 a little N . of N.N.E. This mass, as indicated in our section*, 

 underlies the rocks of the quarry. A little distance south of the 

 edge of the same pit, and about 70 yards from this knoll, are (at 

 present.) outcrops of another rock more or less brecciated. In one 

 reef just close to the edge of the pit-wall an agglomeratic character 

 is very distinct, the fragments, by weathering, standing out from 

 the matrix. Freshly broken surfaces exhibit a mottled structure, 

 which somewhat reminded us of the Kite-Hill rock f. To this suc- 

 ceeds a brecciated rock, now well exposed in the south wall and 

 adjacent floor of the quarry ; fragments, sometimes 4 or 5 inches in 

 diameter, of a speckled rock occurring in a dull greenish matrix, 

 from which they are distinguished by the pinker, redder, or some- 

 times slightly yellowish tint of their ground-colour. This rock 

 seems to pass up — no hard-and-fast boundary being determinable — 

 into the compact, green felstone-like rock, which was chiefly quarried 

 in the older workings. Over this comes a brecciated rock, in which 

 the apparent fragments are parted by a compact streak}- matrix of 

 a purple-red colour. To this succeeds another brecciated rock in 

 which a green or yellowish- green colour predominates, which is 

 followed by another breccia, pinker in hue. This last seems to pass 

 into a dull purplish rock, which is rather fissile, and resembles 

 generally the Sharpley porphyroid, especially that variety which is 

 exposed in the knoll on the moor near Spring Hill Farm, except that 

 the quartzes and felspars are rather smaller in size. This porphyroid, 

 in the upper part, has a very ashy look, and contains fragments 

 which sometimes are numerous. Most of these are typical Peldar 

 rock, but a few are a purple porphyritic felstone, and over this 

 porphyroid comes the main mass of rock, identical with that of 

 Peldar Tor. 



The nature of the last-named has been already discussed. If, 

 then, it be a volcanic rock, we have to investigate the underlying 

 porphyroid. This rock appears to be rather variable in thickness, 

 and to pass almost imperceptibly into the more or less brecciated 

 greenish rock in which the greater part of the excavation is made. 

 Was it originally a lava or an ash ? If the former, the presence of 

 fragments of Peldar porphyroid in its upper part must be explained 

 by supposing it to have broken through a mass of that rock ; but on 

 that hypothesis it is a little difficult to account for the occasional 

 association of the purple porphyritic felstone. The distribution also 

 of the Peldar fragments in all the masses which we have examined, 

 while not absolutely incompatible with the above explanation, cer- 

 tainly accords better Avith the idea of a pyroclastic origin J. Micro- 

 scopic examination of the matrix does not help us very much. 

 The rock evidently has been subjected to considerable pressure. The 



* Oj9. cit. p. 780. 



t The microscopic structure also is rather similar. 



\ They mny liaA'e been ejected from the vent which supplied the lava, and 

 have fallen in advance of it — the Sharpley lava and tufi' coming from a neigh- 

 bouring vent. 



