RAJMEHAL GROUP. 63 



and dense porcelanic rocks are found, frequently of bright red and green colors. 

 These were unquestionably in their original state shales, which have been baked and 

 vitrified by the intense heat of the overflowing lavas. They have not been found any- 

 where in situ, but, judging from the circumstances under which they occur, they appear 

 to be the debris of thin beds of shales which once existed above all the sediment- 

 ary deposits now remaining. 



A very peculiar bluish-grey steatitic substance occurs below the trap which under- 

 lies the grit just noticed. This was only seen in two places near Murrero, in the 

 north-west corner of the hills, and again at the cutting near Sitapahar, on the line of 

 the East Indian Eailway. It is, when dry, of tolerable hardness, has a very greasy 

 feel, and breaks with a conchoidal fracture, but when saturated with water becomes 

 soft and muddy. It is unfossiliferous and appears to be a volcanic mud. 



The next sedimentary beds in a descending order {viz., Nos. 4 and 6 of the gene- 

 ral section, p. 54) are by far the most interesting and important of all this inter- 

 trappean series, inasmuch as it was from these that nearly all the very beautiful fos- 

 sils which have been obtained from these Eajmehal hills were collected. 



These generally consist of fine-grained whitish or greyish clays, or sands passing 

 on the one side into sandstone and on the other into a close fine shale. For the most 

 part, these shales, when of no great thickness, have been baked and indurated by the 

 overflowing traps into a dense ringing porcelanic mass, like biscuit-china, often of 

 the most perfect white colour, and frequently one mass of the impressions of leaves of 

 PalcBOzamia, &c. 



In the majority of cases, these well-marked deposits constitute, as noted, only 

 two distinct beds, but locally these have been cut up by the overflowing of thin sheets 

 of lava ; and in one place (east of Meghi) there are four layers instead of two ; in 

 other places there are three. 



The upper group is thicker than the lower, being frequently 25 to 30 feet, while 

 the lower is not more than 10 to 15 feet in thickness. The upper group is also more 

 sandy than the lower, and the lower portion of it is generally a sandstone — a fine 

 grained, soft quartzose sandstone, in which the impressions of leaves and plants are- 

 preserved with a peculiar yellow color. Of these beds, as of all others in the dis- 

 trict, the upper part, where in contact with the overflowing trap-rocks, has been gen- 

 erally much altered and indurated. In this hardened portion, and also in the less 

 altered and softer parts of the shales, there occur in the greatest abundance silicified 

 trunks of trees. 



The majority of these vary from 1 foot to 18 inches in diameter, while some are 

 seen so much as 3 or 4 feet across. 



Sometimes the rock seems to be made up of a mass of small stems or twigs. 



( 217 ) 



