1835.] and Site of Fossil Bones in the Jumna. 275 



the opinion before advanced, namely, that the force of heat is capa- 

 ble of causing the decomposition of bones, unless shielded by some in- 

 tervening substance, applied during a state of freshness, and conti- 

 nued up to a certain period, the time of which must vary according to 

 the quality of the bone ; but my experience does not enable me to set 

 bounds to the time necessary to render one of any quality proof to the 

 effects of the sun's rays. I imagine, the seasons may cause so much 

 variation, that the exact time necessary for them to continue under 

 this protection, cannot be better defined than between the time of 

 their deposition in a state of freshness, and the extinction of every 

 animal or vegetable property, when they become nothing more than 

 consolidated earth ; (see specimens, the remainder of a pipal tree, 

 Nos. A 3,) and even in this state I am led to believe, that exposure 

 to the sun would cause decomposition, and to this, as well as to the 

 effects of attrition, must be attributed the very few perfect bones found 

 in these positions. I once found the femur of a camel, the middle of 

 which was covered by a large damp stone, the portion covered was 

 perfectly petrified in its whole circumference, whilst both ends were 

 decomposed ; but the absence of fossil remains in the whole section of 

 this general alluvium is more conclusive than any minor proofs that 

 can be adduced. 



Very few specimens of wood occur in these situations. To the rea- 

 sons advanced in explanation of the imperfect state of the bones is to 

 be added the greater degree of brittleness of this substance in a pe- 

 trified state. I have never procured more than three specimens from 

 the kankar shoals, which I will forward with the other specimens of 

 the collection. 



Petrified clay (Specs. 9,) is found generally in small portions, and 

 is transmuted by the same process as the earthy substance, to which 

 wood is reduced previous to petrifaction, (spec. A3,) which to all 

 appearance has every property of indurated clay, the specific gravity 

 of each being nearly the same. 



Composition shingle, or cement pebbles, are produced by the admix- 

 ture of clay or sand in almost every proportion of each : the most com- 

 mon process of the formation is as follows : 



After a heavy shower, the water in its passage through the ravines 

 near the river brings down with it clay in the shape of a thick sedi- 

 ment ; this in many instances, after leaving the mouth of the ravine, 

 has to run over large sand beds before it reaches the river, through 

 which any considerable body of water cuts deep passages or gulleys, 

 which run nearly horizontal 10 to 20 yards, and then fall 4 to 12 feet ; 

 running on again, they fall and run on irregularly, until reaching the 



