GEOLOGY OF THE COOMA DISTRICT, N.S.W. 219 
much anastomosing in the river system. The probable 
main features of the drainage are indicated in the map (fig. 
2). The mature valley now occupied by Pilot Creek marks 
the course of a stream which flowed across the line of the 
present river at Mittagang, and S.H. along the dry valley 
in which is the present Mittagang road, thence south of 
Tillabudgery Trig. Station, across the racecourse, along the 
valley just west of Bushy Hill, and then probably into the 
valley of the present Cooma Creek. This old Pilot Creek 
valley is marked by the remnants of a basalt flow through- 
out its entire length. To this valley there is a tributary 
dry valley starting at a point about three-quarters of a 
mile east of Mittagang Bridge, and running a little east of 
north parallel tothe present Murrumbidgee to within a short 
distance of the S-bend in that river. This valley is cut 
pretty deeply into the schists and gneisses, but is fairly 
mature: it is now tapped and drained into the Murrum- 
bidgee by Butler’s Oreek and another small creek further 
north. 
It is extremely unlikely that the old Murrumbidgee 
should have flowed south through the Berridale fault-block 
along its present very youthful channel. More probably it 
originally flowed S.H. in the present channel of the Umar- 
alla for some distance, then south along the valley of the 
present Rock Flat Creek, and so on to join the Snowy 
River.* When the tilting and other earth-movements 
occurred the direction of flow was reversed and the now 
north-flowing Murrumbidgee began to head back towards 
the south. At the S-bend for some reason or another it 
commenced to cut into the fault escarpment, and a new 
stream was formed which cut across Pilot Creek, captured 
its head-waters, and converted the southern portion of its 
bed into a dry valley. 
* An alternative suggestion is that the river flowed through the dry 
valley between the S-bend and Mittagane, and down southwards through 
the Mittagang road valley (see Fig. 2). 
