49 



Granular marble shows again in cliffs on opposite side 

 of wash-out. Dip S.W. at 40°. These beds continue for 

 180 yards to another small affluent, where the Archaeocya- 

 thinae beds make their appearance with a strike E. 20° S. 



(d) Archaeocyathinae limestones, showing extensive 

 development near the outlet of the gorge. Tlie base of these 

 beds cannot well be determined as the fossils gradually dis- 

 appear, losing their organic structures by conversion into 

 marble or dolomite. This occurs both at the base of the 

 fossiliferous beds as well as at their upper limits.. 



Immediately on the eastern side of the great limestone 

 series, the Parachilna Creek has broken through a great wall 

 of quartzite, which towers to a great height on either side. 

 There follow, in descending order, thick shales with some flags 

 (dip 70°-80°) up to the prominent and peaked hill of quartzite, 

 near the reservoir; underlying which are shales ha\ing a 

 strike almost parallel with the road, and a dip of 90°. These 

 shales are oft-en sharply curved and continue in the section 

 to the mouth of the Oratunga Creek, having a dip of from 

 80° to 90°. From this point, by a sharp bend in the road, 

 the latter follows the strike of the beds, which there have a 

 dip of 75°. The road then crosses the creek and takes a 

 sharp curve round a spur of quartzite, 50 ft. in thickness, 

 with a dip from 70° to 80°. In this angle there is a fault 

 associated with strong V-shaped contortions, the beds being 

 shales with hard, thin quartzites having a dip of 45°. At a 

 short distance from the preceding the road crosses the creek, 

 a second time, where shales have a dip of 60°. At the third, 

 and last time that the road crosses the creek, the shales have 

 a dip of 80° to 85°, with a wavy structure. 



At a distance of three miles from the mouth of the gorge 

 limestones once more begin to show themselves in the section. 

 At a sharp angle of the road, just past Mount Mary, there 

 are beds of pink-coloured limestone seen on the road. Shales, 

 with a dip of 45°, occur for a distance of three-quarters of a 

 mile to the ''Dairy," where the road is close to the Parachilna 

 Creek and is at the foot of the "Big Hill. "(2) The dip 

 decreases towards the ''Dairy." 



Calcareous grits and arenaceous (oolitic) limestones occur 

 very commonly on the western side of the "Big Hill." There 

 also occur thick flaggy quartzit-es, 200 ft. in thickness, over- 

 lain by pure limestone and gritty oolitic limestone: dip S.W. 

 at 25°. These gritty limestones have a great development 

 on the creeks which pass between the road and the Parachilna 



(2) This is quite distinct from a hill of the same name situated 

 between Blinman and Wirrealpa. 



