7S4 B. HILL AND T. G. BOXXET 0>~ THE 



fibrous mica. Of this mineral there are two species: — the one 

 olive-brown, rather strongly dichroic ; the other in larger crys- 

 tals, nearly colourless, with almost unmarked dichroism. showing 

 brilliant colours with polarized and analyzed light, and a strong 

 sodium-line with the spectroscope. Both the micas appear to be 

 orthorhombic : the microscopic structure of the rock much re- 

 sembles that of a minette. "We conclude therefore, since the 

 appearance of the rock in the field seems to prove its sedimentary 

 origin, that it was formerly a finely levigated mud, and has been 

 intensely metamorphosed. 



Correlations. 



To correlate beds such as those described above, without fossils, 

 with very variable lithological conditions, and with much subse- 

 quent alteration, is a most difficult task ; and it is impossible to do 

 more than conjecture: but we think, from what has been stated 

 above, that the following are probably on the same horizon :— 



(i) The Forest-gate pebble and ash beds, the pebble and over- 

 lying grit bed of the Hanging Rocks by "Woodhouse, the pebble and 

 grit beds of the Brande and Swithland, the quartz grits of the Stable 

 Quarry in Bradgate Park, of the Boathouse by Groby Pool, and of 

 the small patch south of Bradgate-House Wood (Stewards Hay 

 Spring) of the Ordnance map. 



(ii) The coarse slate breccias of Blore's Hill (F on the Map), of 

 Holgate Hill and Old John, the breccias of Ulverscroft Mill, of 

 Markfield, of the entrance to Bardon Quarry (of this last we are 

 more doubtful), and at the western end of High Towers. 



(iii) The coarse unstratified ash beds, usually coloured red (as 

 igneous rocks) on the Geological map, of Bensclitf. Chitterman Hill, 

 and Barnby Wood, the eastern ridge of Timberwood Hill, and two 

 isolated exposures, one at the H of Hanging Stones, the other in 

 the kitchen-garden of the Monastery. 



(iv) The quartzites and ashy banded slates and schists of the 

 outcrop near Charley "Wood, Charley church and its neighbourhood, 

 Upper Blackbrook, and Blackbrook Tollgate. 



The sum of the intervals between these horizons, measured along 

 the surface, is slightly over two miles ; while there is in addition a 

 considerable depth, perhaps about 1000 feet, of fine workable slate, 

 seen at Swithland and Groby, overlying the horizon at which this 

 estimate commences ; and the lowe:*t beds of Ives Head seem not less 

 than 1500 feet below the point where the above section tormina 1 

 so that, if the average dip of the beds be taken as 30° (which seems 

 a fair estimate), the thickness of the strata included in our descrip- 

 tion would be at least 7500 feet. 



The principal difficulties in the way of the above classification 

 are — the absence of the Bradgate breccias from Brooinbriggs and 

 Beacon Hill, of the Benscliff ashes from the east side of the anti- 

 clinal, and of almost the whole of the rocks of the north-west corner 

 from every other point whatever. We can only reply that on 

 Broombriggs and Beacon Hill, except at one or two places, expo- 



