TALCHEER COAL FIELD. 69 



in the Atgurh basin all the level countr}' is covered by alluvium, it is not 

 at all impossible that in the latter field representatives of the Damoodah 

 group, &c., may be concealed beneath the alluvial deposit. The hills of 

 Atgurh, in truth, are like islands in a sea of alluvium, which on every side 

 separates them from the gneiss and each other. 



In some of these hills, beds have been observed resembling the clays 

 at Patrapara, the resemblance being strengthened by the occurrence in 

 them of imperfect vegetable remains. 



The alluvium has been frequently alluded to in the preceding pages, 



owing to its troublesome and inveterate tendency 

 Alluvium. 



to conceal the beds and their boundaries. It 



consists of a mixture of sand and gravel, frequently ferruginous or 



kunkeriferous, sometimes both. 



It is of considerable extent and depth. Its greatest observed thickness 

 in the Ouli valley considerably exceeds 100 feet ; and throughout the 

 area of the upper grits, from the denudation of which it appears to have 

 been derived, it abounds in all plains and valleys, excepting those 

 evidently excavated by fresh water, from which it is generally absent, and 

 in which it is never of any great depth. The lower portion of it seems 

 sometimes to pass into laterite, as on the Brahmini. 



Since it contains, so far as observed, no fossils, and has been inves- 

 tigated over a comparatively small ai-ea, it is impos- 



Age as yet undeter- ° i ^ •> i 



B'i^^'i- sible to specify its age. The surface is probably a 



fresh-water accumulation, since, during the rains, the greater portion of it 

 is subjected to inundations from the numerous rivers flowing through 

 the district; but to what depth this character extends, and whether 

 at greater depths any change takes place in its mineral character and 

 composition, are points remaining for future investigation. 



Laterite has but little extension in Orissa. It occurs to some extent 

 „ , „ , . round Cuttack, and frequently borders the hills 



Rocks of chemico-aque- ' 



ouB origin. Laterite. between that Station and Balasore, besides occurring 



