t 85? ] 



XXXIY.— ON THE MET AMORPHIC EOCKS OF COS. SLIGO 

 AND LEITRIM, AND THE ENCLOSED MINERALS 

 WITH ANALYSIS OE SERPENTINE, &c. By EDWARD 

 T. HARDMAN, f.c.s., with MICROSCOPICAL NOTES ON 

 THE SERPENTINE. By Professor HULL, ll.d., f.e.s. 

 PLATE 33. 



[Read June 19th, 1882.] 



Part I. 



The portion of the metamorphic rocks referred to in this paper 

 includes the N.E. extension of the Ox Mountains, from Colooney to 

 the north of Manorhamilton, a considerable part of which forms 

 the southern shore of Lough Gill. 



Besides this principal mass there is an inlying portion protrud- 

 ing through the carboniferous rocks of Rosses Point to the 

 north-west of the principal mountain line and 9 or 10 miles 

 distant from it. The general characters of both agree however in 

 all essential respects. 



1. Ox Mountain Range. — These rocks form a ridge some 3 to 4 

 miles wide, showing a series of irregular peaks semi-rounded 

 by giaciation. The principal heights are about 900 feet, although 

 Benbo Mountain rises to an elevation of 1,365 feet. The other 

 chief elevations are Benbo Hill 849, Rockwood (or Slish Mountain) 

 967, and Slieve Deane 900. South of Lough Gill, Union Wood 

 440 ; and Carrownageeragh to the west of Colooney. The last 

 being 602 feet. 



The north-west boundary of these rocks is very precipitous in 

 places, especially in the district between Ballisodare and Shsh- 

 wood, where there is a cliff boundary about 100 feet high. This 

 marks a line of fault which has been traced from near Ballisodare 

 to Saddle Hill, county Leitrim, a distance of over 20 miles. 



On the south the rocks, although rugged, are not very pre- 

 cipitous, and while it is probable that a fault occurs on this side 

 also, it is not so apparent as on the other side of the range, in 

 both cases bringing down the carboniferous rocks, on the north 

 side (the downthrow being the greatest), the Upper Carboniferous 



