F-RECARBONIFEROUS ROCKS OF CHARNWOOD FOREST. 783 



we are of opinion that even this is only an altered rock*. The hill 

 consists throughout of highly altered rock, into which volcanic 

 breccias enter largely. The porphyritic rock, with the quartz gra- 

 nules and felspar crystals of the lower quarry, corresponds very 

 closely, not only in general appearance but also in microscopic 

 structure, with that of Peldar Tor. The change in character of this 

 rock in passing from the north to the south side of the pit is re- 

 markable ; but there is no sign of a fault down it, and microscopic 

 examination shows a general correspondence in the character of the 

 rock. Both consist of a fine streaky matrix, composed apparently, 

 to a great extent, of comminuted angular crystals of felspar, con- 

 taining larger crystals of the same, both orthoclase and plagioclase, 

 with much epidote, and some viridite of secondary formation. The 

 specimen from the north side seems to have a rather more granular 

 matrix, and has the large subcrystalline quartz grains, which, how- 

 ever, are not quite absent from the specimen collected on the south 

 side. The fragments examined from the breccia on the south side 

 of the pit, as well as one from the breccias forming the upper part 

 of the hill, may possibly be of sedimentary origin ; but the full dis- 

 cussion of these is reserved for the second part of this paper. We 

 may say, however, that their microscopic structure closely corresponds 

 with that of those which they are stated to resemble — the Peldar-Tor 

 and Cadman series. 



19. One isolated patch of rock, entirely different from all others, 

 occurs in the centre of a plantation at Bawdon Castle, nearly in con- 

 tact with syenite. It is a very dark, rather altered grit, containing 

 many small included fragments. Microscopic examination shows it 

 to be a pyroclastic rock. 



The rock of the quarry at Moorley Hill, on the extreme north 

 boundary of the forest, is a series of coarse banded slates or grits, 

 with an occasional imbedded crystal of magnetite. The beds dip 

 " at an angle of 35° true N.E. The cleavage is imperfectly deve- 

 loped" (Jukes). They do not resemble those of Ives Head, near 

 them but on the other side of the anticlinal line. 



The gneiss of Brazil Wood appears in an isolated knoll a few 

 yards distant from a mass of hornblendic granite, which is probably 

 intruded into it. This rock has received full notice from preceding 

 observers. It is quite isolated from and unlike the other rocks of 

 the forest, and may possibly belong to an earlier series. The micro- 

 scopic structure is remarkable. It consists of a fine granular base 

 (doubtless an altered felspathic mineral) with some small grains of 

 quartz, probably of secondary origin, and a large quantity of rather 



* It has been more than once stated that I consider Barclon Hill to show 

 a plug or dyke of felstone. At one time, before I had completed my examina- 

 tion of the pit, or had studied the rocks microscopically, I inclined to this view, 

 and expressed it incidentally in a letter to a member of the Geologists' Associ- 

 ation before their visit to Charnwood. The publication of this letter was quite 

 unauthorized, as I had not come to a definite conclusion on the point. Further 

 examination has shown me that the whole of this igneous patch in the Survey 

 map must be effaced ; and I beg leave to recall this erroneous statement. — 

 T. G. B. 



