Transactions and proceedings of the Royal Society of South Australia (Incorporated) . half a mile distant beyondthe gate which admits to the Woolly Paddock, a small lime- 71 stone is exposed; it has a laminated structure and is under-going change to manganic and ferric oxides: dipS. 10° 30°. ? Tlie Mount Lyall Range extends from the old station,in a north-easterly direction, for a distance of about 3 Mount Lyall (fig. 2) it forms a sharp angle with a rangethat comes down from the north. At the angle is a prominenthill, about 150 ft. in height, which shows a scarp face to thesouth
Transactions and proceedings of the Royal Society of South Australia (Incorporated) . half a mile distant beyondthe gate which admits to the Woolly Paddock, a small lime- 71 stone is exposed; it has a laminated structure and is under-going change to manganic and ferric oxides: dipS. 10° 30°. ? Tlie Mount Lyall Range extends from the old station,in a north-easterly direction, for a distance of about 3 Mount Lyall (fig. 2) it forms a sharp angle with a rangethat comes down from the north. At the angle is a prominenthill, about 150 ft. in height, which shows a scarp face to thesouth-east. This hill is a solid mass of limestone, brownishin colour, dolomitic, and very compact. The section repre-sents the lower beds of the Archaeocyathina© series. Thesebeds follow the strike of the northern range of hills, but theyappear to run out to the northward. It is probable thatthe scarp face of the a fault plane. Tlie hill justmentioned has a dip at the summit N. 10^° E. at 15°. Fromthe top of the hill it could be seen that the beds on the north MZyccll. Fig. 2. Geological Section of Mount Lyall. side of Mount Lyall were much disturbed, dipping at variousangles both to the Mount Lyall Range and also to one another. The peak of Mount Lyall dips at 60°. The north-eastern end of the range is broken by ( ?) two faults. MountLyall peak dips as above, then on the eastern side the dipsomewhat suddenly changes to nearly horizontal. After a fewhundred yards at this level there is a sudden break, M^hen thepurple shales, much crumpled, are thrown down to the faceof the quartzites with a dip N. 20° W. at 35°. A crush-zoneoccupies the fault area for a thickness of about 9 yards. Aseries of underlying dolomitic limestones, purple shales, andquartzites follow with a rising dip, going east, to 50° (seefig. 2). Just round the northern end of the range there isan oblong dyke of intrusive rock. On the eastern side ofthe dyke there is a crush-rock, composed of flag
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectscience, bookyear1912
