47 



The typical structure exhibited by the Flinders Ranges 

 takes the form of broad anticlinal and synclinal folds which, 

 by complicated directions of pressure, frequently produce peri- 

 clinal domes with complementary saucer-shaped depressions, 

 the latter being locally known as ''pounds." The geological 

 section, now under description, is transverse to one of the 

 most extensive dome-structures in the ranges, the centre of 

 the dome being situated, approximately, near the township of 

 Blinman, with the superior beds dipping away in circles around 

 this centre. A few miles to the south of Blinman is the 

 Wilpena Pound, formed by a complete circle of mountains 

 with the gap made by the Wilpena Creek, the only means 

 of ingress and outlet to the basin. At Mernmerna, on the 

 great northern line, the hills on the eastward side of the 

 line form very steep escarpments with rugged peaks, forming 

 the western limits of the Elder and Wilpena Pound Ranges. 

 This precipitous face continues, northwards, to Parachilna, 

 as a fault-scarp, making the eastern boundary of the great 

 rift valley of South Australia in that direction. 



As the present paper is based on a single visit to the 

 locality, and an interval of about sixteen years has passed 

 since the observations were made, the paper is practically 

 limited to the itinerancy and the field notes made at the time. 

 The Geological Section, published herewith, was drawn soon 

 after the authoi's return to Adelaide. The newer, southerly 

 road was followed going out, and the older, northerly road 

 on returning, when the journey was made by coach. 



I. Parachilna Gorge. 



ENTRANCE TO THE GORGE. 



The Parachilna railway station is situated on the plains 

 skirting the eastern side of Lake Torrens, about seven miles 

 from the foot of the ranges. The gap in the ranges, east of 

 the railway station, has been cut by the Parachilna Creek, 

 forming a narrow and very picturesque gorge. In approaching 

 the gorge the first recks met with are limestones that outcrop 

 on the road, near an old house in ruins. These are sub- 

 crystalline, of a coarse-marble kind, much broken and 

 penetrated by veins (dip S. 20° W. at 46°), underlying which 

 are limestones containing Archaeoeyathinae. The country 

 along the face of the great escarpment is much faulted. 

 Following the western escarpment, going south, in a second 

 spur, the fossils gradually disappear in a dolomitic matrix, 

 the fossils occurring in every stage of alteration as they become 

 absorbed into the matrix. [On this spur is an isolated group 

 of sandstone boulders, some of which are of great size.] In 

 following the line of outcrop, southwards, there is a narrow 



