571 



mount (extending from the purple-slates to the tillite) be 

 continued downwards to the underlying bed, then the 

 quartzite which occupies that position must be regarded as 

 synchronous with the quartzites that underlie the tillite near 

 Adelaide. But at several points in the outcrops of the 

 Mount Remarkable quartzite the stone includes clastic 

 ilmenite, occurring in dark lines, and is current-bedded. In 

 the case of one stone picked up near the Cathedral Rock, the 

 ilmenite forms at least one-fourth of the mass. The only 

 horizon where such current-laid ilmenite is known to occur 

 in the Lower Cambrian of South Australia is in the basal beds 

 of the series, where it is a constant and very characteristic 

 feature. The difficulty in the way of referring the Mount 



ILLOCHRA. 

 PLAINS 



Geological Sketch-section through Mount Remarkable to show 

 probable duplication of the main quartzite by faulting. P.P'. 

 Purple-slates Series. L.L'. Main (Brighton) Limestone. S.S'. 

 Siliceous Limestones. R. Ribbon (Tapley Hill) Slates. T. Tillite. 

 Q. Quartzites. SI. Slates. 0. Crush-rock. The dotted lines show 

 the extension of the beds over the mount before faulting took 

 place. 



Remarkable quartzite to the same horizon is very great, as 

 the tillite, which rests on the quartzite of the mount, is from 

 8,000 feet to 10,000 feet (perhaps more) above the horizon 

 of the ilmenite grits of the basal beds. If a stratigraphical 

 accordance can be established between the respective ilmenite- 

 bearing beds, then it might be found that quartzites of very 

 different geological horizons have united to form the main 

 axis of the mount. 



