4b* mallet: geology of darjiling and western duars. 



great thicknesses of soft massive sandstone unmixed with other rocks 

 also occur, especially towards the upper part of the group ; the clunch 

 and shaly beds are most abundant towards the lower part. 



Fossil stems are frequent in the sandstone. They occur up to a 



foot or so in diameter and 10 or 15 feet long, 



Fossil stems : lignite. 



being generally more or less flattened by pressure. 

 In most of them the original woody part is replaced by carbonaceous 

 sandstone, while the bark is represented by brittle jetty lignite, breaking 

 with conchoidal fracture. In some, however, carbonaceous sandstone 

 and lignite are interbanded with each other throughout the entire thick- 

 ness of the stem, in very irregular layers parallel to the structure of the 

 wood. Occasionally the stem consists entirely of lignite, and is then 

 generally squeezed quite flat. Besides such recognizable stems, little 

 irregular masses and strings of lignite are often met with in the sand- 

 stone, but never of any size, the largest I ever saw containing less than 

 2 cubic feet. 



There are, however, a few beds of coal in the Tertiaries ; not jetty 

 lignite with conchoidal fracture, but soft and flaky, 

 very much resembling the Damuda coal in outward 

 appearance. The possibility of its being Damuda caught up in the Ter- 

 tiaries suggested itself to me, but further examination convinced me that 

 it is not so. At least two such beds are met with on the cart road, one 

 of which is a lenticular mass 6 feet thick, but only extending for a few 

 yards laterally ; it may represent a local accumulation of drifted vege- 

 table matter. The other varies, where exposed, from 9 to 2 inches in thick- 

 ness and what is possibly the same bed is exposed at two or three 

 points lower down the winding road. An assay of the coal from the 

 second bed shows that it contains 43*2 carbon, 19' 6 volatile matter, and 

 37*2 ash, or nearly half as much volatile matter as carbon. The 

 hio-hest percentage of volatile matter in the Damuda coal is less 

 than a fourth that of the carbon, and the average only one-eighth. 

 These Tertiary coal beds are by no means common, not more than half 

 ( 4.(3 ) 



