212 Col. McMahon — Granite of the Himalayas. 



the street again Jan. 12, 1775, and again Feb. 26, 1776. This 

 Nailbourne ariseth at Dean, in the parish of Elmsted, and at Duck 

 Pit in the parish of Waltham. This by Thos. Page." From other 

 data this Nailbourne ran in Jan. 1860, Feb. 1861, 1864, to June, 

 1865, and slightly in 1866, 1869, and Jan. 1873. 



Notes on a Well at Elmsted Yicarage. Communicated by Eev. G. 

 A. Collett. "This well was sunk in the Vicarage garden in 1884, at 

 an elevation of 500 feet O.D. Water was first reached at 180 feet. 

 Waiting for this to lower, the well was continued to 243 feet, where 

 a good head of water was met with. The strata met with were firstly, 

 11 feet of diluvial matter, stones, clays, etc., called locally ' clay 

 pillars.' All below this, Chalk without flints, with joints few and 

 far between, the Chalk so hard that it had to be blasted with gun- 

 powder, no need to 'steen.' We sent up at 58 feet some palatal teeth 

 of fish, and lower down fragments of Inocerami. Below 220 feet 

 the Chalk was more jointed and easier worked. The springs rise and 

 fall here in a very wonderful way, they are usually highest in May 

 and fall till January, when they begin to rise again. In December, 

 1884, I ran my well dry, but kept sounding it in January, 1885, 

 expecting water. On the 13th it was dry, next morning I found 

 fourteen feet of water, which soon increased to 40." 



In the tabulated list of wells appended, I have given the height 

 above O.D., the depth of well, and the water-level (where this 

 information is given), but in most cases, especially in bored wells, 

 the latter is not very conclusive. For other particulars of well- 

 sections I must refer my readers to the Memoirs of the Geological 

 Survey, vol. iv. pt. 1, by Mr. W. Whitaker, B.A., F.G.S., and the 

 Quarterly Journal of the Geological Society, vol. xlii. p. 26. I have 

 confined my observations chiefly to the water supply. 



I am indebted to those gentlemen whose names appear in the 

 Appendix of Well-sections (p. 211) for much valuable information. 



III. — The Gneissose-Granite of the Himalayas. 



By Colonel C. A. McMahon, F.G.S. 



Introduction. 



n"^HE cause, or causes, which result in the foliation of igneous 

 I rocks is a subject which at present occupies the attention of 

 many geologists, and seems likely, in the near future, to lead to some 

 discussion. In view of this, a short account of the foliated granite 

 of the Himalayas may be of interest. It may be as well, however, 

 to preface my remarks by saying that I believe that foliation may be 

 produced in several distinct ways, and the explanation which I offer 

 of the mode in which the foliation of the Himalayan granite has been 

 brought about is only intended to apply to the case of that granite. 



In the following pages I propose to give a brief summary only of 

 some of the more important results worked out in detail in a series 

 of papers published in the Eecords of the Geological Survej'^ of India; 

 and to add thereto a brief consideration of the question whether the 

 foliation of the gneissose-granite of the Himalayas was, or was 



