CHAPTER III. 



GEOLOGICAL FORMATIONS. 



In order to present as complete a review as possible of the 



geological history of the Northern Shan States, 

 Introductory remarks. j-r , • 1 1 n • ,i 



certain formations are included m the present 

 description that are not actually found within the borders of the 

 States, the boundaries of which have been drawn for political 

 rather than physical reasons. These formations, the gneisses and 

 associated crystalline rocks of the Euby Mines District and of 

 Mandalay, constitute the foundation upon which all the succeeding 

 series of strata have been built up, and are therefore included in 

 the list given below. Much still remains to be done in working 

 out the geological relations and structure of these ancient rocks in 

 the field, and of their chemical and microscopic characters in the 

 laboratory ; for hitherto they have been examined only in the vicinity 

 of Mogok, the centre of the ruby mining area. The character 

 of the rocks as seen in the field in this neighbourhood were 

 studied in 1887 by Mr. C. Barrington Brown, who was sent out by 

 the Secretary of State for India for that purpose, and the collec- 

 tions of rock specimens and minerals made by him were sub- 

 mitted to Professor J. W. Judd, who made a searching examination 

 of their petrographic and genetic characters ; the result of their 

 labours being a joint paper published in the Philosophical 

 Transactions of the Koyal Society, 1 to which further reference will 

 be made below. 



My own acquaintance with these crystalline rocks has been con- 

 fined to one or two rapid traverses across the country occupied by 

 them, and my observations were for the most part made with the 

 view of ascertaining and mapping the boundaries of the area. I 

 was therefore not able to collect sufficient material or data for a 

 complete and critical account of the petrography. 

 T . ± , , x . The formations that have been identified in 



List 01 formations. . 



the area surveyed are the following, m des- 

 cending order : — 



1 The Rubies of Burma and Associated Minerals : their Mode of Occurrence, Origin, 

 and Metamorphoses. A Contribution to the History of Corundum. Phil. Trans Roy 

 Soc. London, Vol. L87A, p. 151. 1897. 



'For an abstract of this papor see Proc. Roy. Soc. London, Vol. LVll, p. 387. 



