ECONOMIC GEOLOGY. 91 



80°, followed by brown pyritous and carbonaceous shales with sandstone, 

 dipping at 60°. Many of the cracks in the massive sandstone are filled 

 with semi-inspissated petroleum, which also impregnates the rock itself 

 in places. From some cracks it is seen to ooze in minute quantities, and, 

 at certain spots in the river adjacent, globules of petroleum rise at fre- 

 quent intervals to the surface, as well as streams of marsh gas bubbles. 

 Petroleum and gas issue from the bed of the river close to the above- 

 mentioned shales also, the total thickness of rock from which they are 

 given off being over 100 yards. 



(16.) Petroleum slowly exudes from between the cracks in the coal 

 of the %' \\" seam in the Hil Jan (p. 70). 



(17.) Two or three hundred yards lower down-stream than the 1' 4" 

 seam in the Disai valley (p. 77), petroleum rises from the bed of the 

 nalla in small quantity. 



Iron. 



The principal iron ores found in the area under description are clay- 

 ironstone from the coal measures, and an impure limonite from the Sub- 

 Himalayan strata. The former generally occurs in oblate nodules vary- 

 ing in size from that of a walnut to the bulk of a man's head, but lumps 

 considerably larger than this also exist. When freshly broken, the 

 nodules have a light-grey color, which changes after a time to a brown 

 tint from the peroxidation of the iron. They are generally covered by 

 a shell of hydrous oxide, from the character of which some idea can be 

 gleaned as to the purity of the specimen. The ore is also found in thin 

 bands, interstratified with the shales and sandstones. 



The following percentages of iron have been found in samples from 

 different localities : — 



Percentage of iron. 

 Nodular clay -ironstone from near Tirugaon ... .. 401 



» „ Tel Pung ... , ... 32-2 



99 9> 99 99 99 99 •*. ... 22*1 



Layer of clay-ironstone, west of Tel Pung ... ... 236 



Not unfrequently, masses of a superficial ferruginous conglomerate or 

 breccia are found, where hydrous ferric oxide, deposited by water 



( 359 ) 



