1050 Remarks on the Geology, $c. [Dec. 



of the transition series, into the highly crystalline slate, which is 

 composed almost entirely of mica, or into chlorite slate, mica slate, 

 &c. renders, if the individual observations are confined to this place 

 alone, the determination of the age of the strata in general, impossible. 

 In fact, the whole of the rocks in the neighbourhood of Simla ap- 

 pear to be more or less altered, but all belonging to one grand group, 

 viz. the transition. To make out this point, we must proceed north- 

 ward from Simla towards Kotgur, where ample means will be 

 found to settle it. The changes observed are quite similar to those 

 exhibited by the grey wacke in the south of Scotland, when in 

 contact with Plutonian rocks.* In examining the neighbourhood 

 of Simla, we were much assisted by Dr. Macleod, who being inti- 

 mately acquainted with all the finest, most interesting, and best ex- 

 posed sections, at once directed our attention to them, by means of which 

 we were in a comparatively short time enabled to acquire a thorough 

 knowledge of the district. To him we beg here to acknowledge 

 our great obligations, and to return our grateful thanks. 

 The rocks met with in the neighbourhood of Simla, are, 



1 Grey wacke, 



2 Grey wacke slate, 



3 Clay slate, 



4 Chlorite slate, 



5 Mica slate, 



6 Quartz rock, 



7 Syenite, 



on both sides of Simla valley, whose direction proceeding down- 

 wards is at first nearly due east and west, it then takes a turn to the 

 south west ; there is clay slate >, on its east and by north side we 

 have the Jacko mountain, reaching to a height of 8,300 feet above 

 the level of the sea. It is entirely composed of clay slate, in many 

 places as near ; and at the summit, we meet with large embedded 

 dykes of quartz rock.t The ridge upon which the Simla bazar 



* Journ. on the Geology of the Criffel Kirkbran and the Needle's Eye in Galloway. 

 Wern. Tran. vol. IV. Dr. Grierson on the mica of Galloway. Ibid, vol. II. and 

 Hay Cunningham, locis citatis. 



f The Jacko is the highest mountain met with in the neighbourhood of Simla, 

 it is considered to be about 800 feet above the Simla bazar. By experiments made 

 conjointly with Dr. Macleod, with thermometers and boiling water, we ascertained 

 that his house, situated at the foot of Jacko, was 7,800. By similar experiments we 

 ascertained the height of Subathoo 4,480 (Mr. G. Clerk's house at Bunnassur 5,600) ; 

 on all occasions we used rain water if it (or snow water which is the best) is not used, 

 the result given is usually inaccurate, common spring water containing a quantity 

 of foreign ingredients, it ought therefore never ; if possible, be had recourse to. 



