68 WYNNE : GEOLOGY OP KUTCH. [PAET I, 



of eruption, may be inferred from the fact that some of them, so soft and 

 Identity with lava of tough as to be easily cut with a knife, are identical 

 ^ ^^' with specimens from dykes, or from " gites de 



contaef in intrusions, occurring either alone or associated with the 

 ordinary igneous rocks intersecting the Jurassic beds of the interior of 

 Kutch; these traps doubtless occupying channels through which some of 

 the overlying flows found access to the surface. 



The white beds of these rocks are often very similar in af)pearance 

 to that which Mr. Blanford describes as laterite without the peroxide 

 of iron near the Taptee, (Mem., Geol. Surv., India, Vol. VI, p. 210). 



The volcanic looking varieties, both purple and lighter coloured, 

 when dry fuse with" some difiiculty before the blow pipe into a black 

 and white speckled glassy substance on the edges. But some small 

 waxy, greenish white, steatitic-looking blotches in one variety (from a 

 mass of intrusive trap at Ruttria) do not change colour, becoming 

 but slightly vitrified or rounded on the edges, and yielding less readily 

 to the blow pipe than their purple matrix, which decomposes quickly and 

 has a saline taste. 



The more evidently mechanically formed aqueous beds of this 

 sub-nummulitic series, though intercalated with the othersj prevail most 

 in its upper part ; but laterites of slightly diflFering varieties range 

 through the series, sometimes forming the basal, sometimes the upper- 

 most bed; while ferruginous bands of very lateritic aspect appear in 

 the tertiary series at some distance above the whole group. 



The laterites are earthy, compact or nodular and scoriaeeous look- 

 ing, sometimes so highly ferruginous as to be- 

 Laterites. 



come an iron ore (anhydrous peroxide), which in 



part furnished material for the iron manufacture, formerly carried on to 

 some extent in Kutch. They vary somewhat in texture, but often 

 ( 68 ) 



