Prof. T. G. Bonney — North- Western Charnwood Forest. 547 



a mica than a chlorite. In this ground-mass are scattered crystalline 

 grains of quartz and of a reddish felspar, ranging up to about one 

 quarter of an inch across. But for microscopic details I may refer 

 to what has been already published, 1 as well as for those of the 

 Sharpley porphyroid, which has a rather compact purplish 

 ground-mass. This, under the microscope, is fairly clear with 

 ordinary light, though containing many granules of a dark iron oxide, 

 and with crossed nicols shows a speckled structure, suggestive of 

 devitrification, interspersed by a few tiny felspar laths, probably 

 a plagioclase. In fact, under the microscope, a ' spotty ' structure 

 characterizes the one rock, a ' speckly ' structure the other. But, as 

 formerly mentioned, the Peldar rock seems occasionally to put on 

 a Sharpley aspect, and the spots in the one, though fairly plain with 

 ordinary light, almost disappear with crossed nicols, as if it might 

 pass into the other. 



In 1891 we saw, as already stated, on the more northern side of 

 the middle 2 quarry at Bardon Hill, fragments of the Peldar porphyroid 

 in a rather schistose and brecciated compact purple porphyroid, then 

 supposed to be a volcanic ash, the material of which had a general 

 resemblance to that at Sharpley, and was practically identical with 

 one which occurred in the breccias of Ratchet Hill and of other 

 places in the Forest. Our facts were correct, but not our interpreta- 

 tion of them, as can be most quickly explained by a brief account of 

 our recent observations. In April we saw but little of the compacter 

 purplish porphyroid, the place of which seemed to have been taken 

 by the oi'dinary greenish rock of the Bardon quarries, but specimens 

 collected prior to 1891 confirm our notes that the former varied from 

 an almost compact rock, indistinguishable from some fragments 

 observed on Ratchet Hill and elsewhere, to a porphyroid onlv 

 differing from that of Sharpley by its smaller crystals of felspar and 

 quartz. In this rock, to which we then assigned a pyroclastic origin, 

 We found "fragments and possibly lenticular streaks" of the Peldar 

 porphyroid to be fairly common, 3 and in April last we observed 

 similar occurrences in the ordinary Bardon rock, and a sharp junction 

 between masses of the two could be traced at one place both on the 

 floor and in the wall of the pit. We came also to the conclusion that 

 the compact and the brecciated varieties of the Bardon rock passed one 

 into another without any break, and that in the latter the boundaries 

 of the fragments were sometimes not very definite, for in one variety 

 they almost resemble reddish clouds on a dull green ground. Their 

 colour also exhibits the same uncertainty, but the breccias with 

 yellowish-green fragments seem now less abundant than those with 



1 Quart. Journ. Geol. Soc, vol. xxxvi, pp. 342-5, 1880. 



2 Now the fourth, counting upwards from the lowest. The quarry in 1878 

 was divided into two stages. In 1880 one was opened a little farther down the 

 hill, so the middle quarry of 1891 (Q.J.G.S., vol. xlvii, p. 86) is the lower of 

 our earlier papers. There are now six quarries one above the other, the fourth, 

 counting upwards, corresponding with our 'middle', and two quarries (besides 

 trial holes) on the north-western side, one of them less than 100 feet below the 

 summit (912 feet). 



3 Quart. Journ. Geol. Soc, vol. xlvii, p. 82, 1891. 



