67 



At half a mile up this creek a thick limestone with 

 wavy structure occurs (dip W. 10° S.), and is overlain 

 by purple shales. Tlie latter are overlain by other 

 thick wavy limestones that form a prominent hill and cross 

 the creek near a group of gum trees; the dip in creek is S.W. 

 At 300 yards further up another bed of wavy limestone crosses 

 the creek, near the centre of which a large block of blue lime- 

 stone (3ft. in length) thickly studded with Archaeocyathinae 

 rested, but it had no stratigraphical relationship with the bed 

 i7i situ. Overlying the last-named limestone are more purple 

 shales, and, by folding, the same wavy limestone, underlying 

 the. purple shales, is brought into the creek again, higher up. 



The creek in which the above observations were made is 

 a small tributary of the main Wirrealpa Creek, which latter 

 passes close by the Wirrealpa Head Station, and according to 

 the pastoral map, is a continuation of the Artimore Creek, 

 which takes its rise at the Patawarta Hill. Numerous loose 

 examples of the Archaeocyathinae limestone were observed 

 both in the wash of the small creek and on the shelving banks 

 that bordered the creek. While I could not locate the parent 

 roek, they are, possibly, local in their origin, as the creek 

 in which they occur is only about 2 miles in length. They 

 may have been derived from some of the thinnish beds of 

 limestone that cross the creek, and which are much broken 

 up, or, possibly, from the main Archaeocyathinae limestone 

 further afield. The countiy, for miles around, is composed 

 of purple shales, sandstones, and limestones. One piece of 

 fossiliferous rock picked up in the creek was composed almost 

 entirely of long lath-like organisms, the nature of which has 

 not been determined. The creek will well repay further 

 investigation . 



XI. The Obolella Limestone on the Road to the Old 

 Wirrealpa Station. 



Followed the Blinman road for half a mile to the junction 

 of the track leading to the old Wirrealpa station buildings, 

 passing over purple shales, with dip W. 20° N. Following 

 the old road over the first rise (low), flags outcropped, with 

 a dip W. at 33°. Second low rise, thin impure limestones 

 (•dip W.)- that are neither oolitic nor fossiliferous. Several 

 such thin-bedded impure limestones occur interbedded with the 

 purple shales and arenaceous flags. The strike becomes 

 S. 20° W. (dip W. 20° N.). The road crosses a tributary 

 of the Wirrealpa Creek in which good sections of purple 

 shales and flags are seen: dip N.W. at 30°. In a low rise 

 to the westward of this creek impure streaky limestones occur. 

 In a second small tributary (east of the high rise) calcareous 



