BY T. GRIFFITH TAYLOR. 329 



synclines and anticlines. In fact here we may have positive 

 evidence of the Tertiary folding into which the CuUarin or Lake 

 George Fault has passed at its southern extremity. 



iii. The Cullarin Fault. 



Leaving the description of the central — true lake-bottom — 

 portion of the area to a later section, an explanation of the 

 above phenomena, together with further evidence of a convincing 

 nature will now be given. To anyone versed in geology, the 

 thirty mile scarp constituting the Cullarin Range, especially 

 when seen from an elevation at some distance, is inexplicable 

 €xcept as a fault scarp. Probably the scarp originated as a 

 succession of small faults along the same plane, extending over a 

 considerable period. Indeed the northern scarp is much more 

 -abrupt (having slopes reaching 45° in places) than the southern, 

 Bungendore, portion. One may reasonably suppose that the 

 tectonic action was more vigorous to the north and extended to 

 a later geological period. 



The geological features of the district are comparatively simple. 

 With the exception of a few square miles of country near 

 Governor's Hill (east of the Lake) where there is an interesting 

 series of eruptive rocks,* the rock consists of slates and phyllites 

 having a fairly uniform strike nearly north and south, the dip 

 being nearly vertical sometimes to the west (Geary's Gap 70°) or 

 again to the east (Native Dog 63°). On the eastern shore these 

 rocks outcrop within the edge of the Lake, but on the west the 

 slates end abruptly at the silt. A certain amount of talus from the 

 hills is distributed at intervals along the western shore, but wells 



* This area is roughly indicated on the map (Plate vii.). Rocks of two 

 types are present. Granite of a somewhat porphyritic nature, showing some 

 evidence of regional metamorphism in the shape of banded felspars, etc., is 

 fringed (see fig. 1) by a complex series of basic and ultrabasic rocks ranging 

 from dolerite to picrites and serpentines. The latter are coated with con- 

 centric layers of secondary lime (travertine). This outcrop would seem to 

 be worthy of investigation by geologists interested in differentiation. 



