RED CLAY ZONE. 53 



approximate average, but it has in places been found to measure even less 

 than 20 feet. 



Conditions. — With the deposition of this red zone things must have 

 changed again, and locally so much that its regular succession was much 

 obscured. The water in which it was deposited was charged no doubt 

 with ferruginous matter, whence the colour it now assumes. The lowest 

 layers alternate clearly with the gypsum for a short space (just a few 

 feet); a certain amount of variety is indicated by the local presence of 

 sandy materials, and the upper layers containing nummulitic bands ; the 

 whole group would seem to link the nummulitic and gypseous groups 

 into one series. 



Minerals. — On the horizon of the harder bands near the -top of the" 

 clays, a sandy bituminous layer was observed in a stream gorge west of 

 Muzdukkai hill. It varied from 1 to 3 feet in thickness, and seemed so 

 saturated with mineral-oil as to increase its weight, yet this did not 

 seem to exude. This, the pisolitic hsematite layer, some narrow gypseous 

 strings, and thin veins of sulphate of baryta, with some small concretions 

 stained with green carbonate of copper, were the only minerals observed 

 in the group. 



( 157 ) 



