GEOLOGICAL RECONNAISSANCE OF THE STIRLING RANGES. 97 



measurement is worthy of more attention than would 

 otherwise be the case. Taking all these facts into con- 

 sideration there seems to be a very strong probability of 

 the escarpment in question being due to a heavy fault 

 throwing northwards, that is, inwards towards the range. 

 In the hill about a mile and a half south of Moingup Spring 

 the highly jointed ripple marked quartzites dip at very 

 gentle angles to the south-south-east. This fact is very 

 definitely established by the relationship of outcrop to 

 contour, though, on superficial observation, one would be 

 inclined to determine the dip as being steep towards the 

 south-east. It is probable in this case that the apparent 

 north-east to south-west strike is due to local alteration of 

 the quartzite by secondary silicification along a joint plane 

 running in that direction. 



In the lower slopes of Yungermere the dip of the quartzite 

 bands is south 30° east at from 30° to 35°. Higher up in 

 the overhanging cliff just below the summit it is south 40° 

 east at 47°. This local abnormality of dip does not seem 

 to conform with any others in the vicinity, and is probably 

 due to a fault or sharp flexure running transversely through 

 the range. It is worthy of note that this ridge is the 

 eastern boundary of The Pass, and, though it is suggested 

 below that The Pass is an erosion feature, it is quite likely 

 that the erosion has been influenced by this structural 

 line of weakness. 



Just below the eastern summit of Warrungup the beds 

 show a dip of south 30° east at 5°. The dip is slightly 

 irregular and rolling, but is everywhere very small in 

 amount. Several remarkable structural features are 

 exhibited in the fine cliff sections of this peak. In one 

 place, very clearly defined contemporaneous erosion of one 

 of the thin quartzite beds is shown. This is illustrated 

 to scale in fig. 2. 



G-August4, 1920. 



