DieCAN TRAP mON-CLAY. 207 



tions. The ferruginous summit bed displays a peculiar structure, for 

 instead of showing- the ordinary horizontal or approximately horizontal 

 Tubulated structure of position of the vcsicular cavities in the mass, it 

 iron-c ay. -^ permeated by vertical tubuli running nearly 



through it. The upper ends of these tubuli are empty for a little 

 distance, giving the surface a pitted appearance, but the tubes are 

 generally filled with lithomargic clay, and have their walls lined with a 

 glaze very like that so frequently met with in the vermicular cavities of 

 ordinary laterites. The tubuli vary in diameter from 5 to f of an inch, 

 but are generally less than | an inch across. Their height depends upon 

 the thickness of the bed, and the glazed sides show much statactitoid 

 waviness of surface. In the lower parts of the bed the tubuli are less 

 distinct. There can be little doubt but that the formation of these 

 tubuli is due to the action of percolating water. This structure is not 

 so commonly met with as the rudely-bedded quasi-stratified forms in 

 which the vesicular and vermicular cavities are rather horizontally 

 disposed. 



The section seen in Paizargarh hill shows a thick-bedded mass of 



iron-clay with little or no tubulation, resting on 

 Paizargarh section. 



a clayey trap (?) of generally grey or purplish 



color, finely streaked and mottled with reddish-brown, orange or dull 



yellow. The vesicular markings noticed at Wallabgarh are seen here 



also, but are much less common. 



A very peculiar pisolitic form of the iron-clay was observed in 



several places, notably on the Yellurgarh, on Bailur 

 Pisolitic iron-clay. 



(Byloor) trigonometrical station peak, and on 



the Kasarsadda ridge south-west of Chandgarh. Where this pisolitic 

 structure supervened, the rpck was seen to have a decidedly jaspideous 

 texture and look. The color of this form of iron-clay varies from pale 

 brownish pink to bright or deep-red, or purple, according to the percent- 

 age of peroxide of iron included. 



( 207 ) 



