334 THE LAKE GEORGE SENKUNGSFELD, 



The river-courses have been largely influenced by the fault. 

 The Molonglo River being situated toward the southern extremity 

 of the fault plane — where the latter was probably of much 

 smaller dimensions, possibly only a fold — has defied the tectonic 

 changes to alter its course, and it has eroded a deep gorge in the 

 " uplift " side of the fault, and, its course being independent of 

 present land contours, the stream is of the antecedent type (see 



rig.3). 



The small streams running down the face of the fault 

 are typically obsequent, since they flow directly against the main 

 slope of the country (which normally falls to the west). Grove 

 Creek, Geary's Creek, &c., are of this character. As pointed out 

 previously, the small rivers of the east coast of the Lake (Murray, 

 Taylor, Deep Creek, ttc.) were originally united, but their lower 

 portions are now buried deep in the silt, and therefore they 

 belong to the betrunked class of rivers. Brooke's Creek for 

 much of its path flows through fairly deep gorges. This tends to 

 support the theory that the western side of the fault has partici- 

 pated .slightly in the earth-movements. Not unusually the scarp 

 of a large fault has been elevated absolutely as well as relatively, 

 and this would appear to be the case at Lake George. If so, 

 then Brooke's Creek is a revived river. Yass River, flowing 

 normally to the west, maybe taken as a specimen of a conseq^ient 

 river. To the north of the Lake, the Currawang Creek flows 

 nortii-west for most of its course, and then bends back to the 

 south. It is extremely probable that this creek originally 

 formed portion of the Wollondilly system, but, owing to the 

 depression of Lake George, it has been captured by the Windera- 

 deen Creek, and now runs into Lake George. As this deviation 

 is due to causes that acted subsequently to tiie establishment of 

 the main slope, this river may be said to be subsequent. In brief, 

 in this comparatively small area we have examples of the six 

 main river-types, consequent {Yass), obsequent {Grove Creek), 

 subsequent {Currawang), betrunked {Murray, d'c.),, revived 

 {Brooke's), and antecedent {Molonglo). Finally, the " Lake 

 George " is a splendid example of what has been termed a daad 

 river. 



