549 



rises for an additional 100 feet. Another perpendicular face 

 of quartzite is seen on the opposite side of the creek, at a 

 higher level, and from these respective sources very large 

 screes are formed. The stone is slightly felspathoid and, in 

 places, carries clastic ilmenite. From the crushed and highly- 

 jointed condition of the stone the dip is somewhat obscure 

 and variable, but several readings gave W. 20° S. at 70°. 



At the southern end of the mount another peaked face 

 of quartzite occurs, which is locally known as the "Gibraltar 

 rock." It has a perpendicular height of about 200 feet, and 

 forms part of the faulted face on that side. The stone is a 

 medium-grained siliceous quartzite, carrying more or less 

 clastic felspar in its constituents. Dip, S. 20° W. at 66°. 



In only one instance, so far as known, does the Mount 

 Remarkable Creek intersect the main quartzite of the mount. 

 It is at the most westerly loop of the stream — the second loop 

 from the southern end of the mount. At first sight the rock 

 appears to have a low angle of dip, but on a close examination 

 the chief divisional lines prove to be joint planes, and the 

 true dip is got from the planes of sedimentation, which, 

 though often obscure, was found in places to give the reading 

 of N. 10° E. at 80° 



Inasmuch as the quartzite passes beneath the tillite on 

 the western flanks of the mount, it occupies a similar strati- 

 graphical position to that of the flaggy and laminated 

 quartzites that underlie the tillite in the neighbourhood of 

 Adelaide, and on a question of natural sequence should be 

 regarded as the equivalent of those beds. The abnormal 

 thickening of the quartzite near the centre of the mount 

 will be discussed later. 



3. The Tillite. 



The main quartzite of the ridge ends abruptly at the 

 southern extremity of the mount in a sheer face of rock, 200 

 feet in height ("Gibraltar Rock") — as already described. A 

 quarter of a mile further up the creek the Cambrian glacial 

 beds, or tillite, make their appearance in the left bank, over- 

 lying the quartzite. The "spoor" of these beds was observed 

 among the detrital material of the creek below Melrose, and 

 was followed up stream till the parent rock was reached. 

 The loose boulders of tillite bear a certain resemblance to the 

 boulders derived from the brecciated rocks, but the matrices 

 of the two kinds of rock are different ; and further, while the 

 crush-rocks are auto-clastic the tillite includes embedded 

 stones of diverse origin. 



These glacial beds are highly typical of the Cambrian 

 tillite as seen in other parts of the State, but the included 



