19 8 



MR. J. PARKINSON ON THE GEOLOGY 



[May 1 90 1 



13. Notes on the Geology of SotTTH-CENTRAL Ceylon. By John 

 Parkinson, Esq., F.G.S. (Read January 9th, 1901.) 



MATALE 



SKETCHMAP 



SOUTH CENTRAL 

 CEYLON. 



I. Introdfction. 



The following notes are the result of a tour of a few weeks' 

 duration i n the south-central parts of Ceylon. The time spent in 

 the island was brief, and the work was done entirely upon inland 

 sections ; but in many places the exposures of rock are good, 

 especially along the lines of railway. Petrological descriptions of 

 Ceylon rocks are not wanting, but details of their field-relations are 

 few, and it is hoped that the following paper may direct attention to 

 the interesting problems which are likely to arise from such an 

 investigation. 



II. The Gneissoid Granulites. 



(a) On the Ceylon Government Railway: from E-a'm- 

 bukkana eastward in the direction of Alagala. — Leaving 

 the station at 



Rambukkana,and Fig. 1. 



proceeding along 

 the metals, we 

 walk over country 

 which is flat, or 

 nearly so, for 

 about| mile,when 

 we come to a small 

 cutting. Here is 

 exposed a rather 

 coarse ^ granitic 

 rock with pinkish- 

 brown felspars up 

 to '3 inch across. 

 In about 6 yards 

 this gives place 

 to one more finely 

 grained, rather 

 saccharoidal in 

 appearance, and 

 speckled with 

 patches of mica. 



On the opposite 



side of the rail- 



way-line the rock 



is banded, but not in the clear even way which, for instance, 

 characterizes the gneiss on the south side of the St. Gotthard Pass. 

 The darker parts are rich in hornblende and brown mica, and 



"^ Granite and granitic are used merely as field terms; as will be seen, 

 the structure of the rocks here described is not that of a granite. 



SCflUE 



16 miles= 1 inch. 



Hornblende and 

 Pyroxenc-Granulites 



iATTO 



t 



