326 Albert V. James.- 



valley. This also has the effect of sharpening the spur, and the- 

 placing iof the flood plain, not at the end of the spur, but on the- 

 down-valley side of it. (2a.) 



Meander Belt.- — In youthful streams, such as Deep Creek, the 

 belt of Avandering and the meander belt coincide wi.th one another. 

 The stream by lateral swinging widens its meander belt, but this 

 tendency is checked by (a) the down-valley sweep of the meanders 

 (which would eventually cut through the spurs), and by (b) the 

 formation of new channels at flood time across low spurs. 



Reldtion httwetn Radius of Meander and Volume of Water. — 

 W. M. Davis has sliown (2a and 9), that the radius of a meander, 

 where slope and load are equal, is proportional to the volume of 

 Avater. This is exemplified in Jackson's Creek, Deep Creek and the 

 Maribyrnong River. Jackson's Creek has a sliglitly smaller- 

 volume than Deep Creek, and the radii of its meanders are slightly 

 smaller than those of Deep Creek. Similarly the radii of the Mari- 

 byrnong meanders are considerably larger than those of the- 

 creeks. 



Hanging Valleys. — Excellent examples of hanging valleys are' 

 found along l>oth Jackson's Creek and Deep Creek. In every case- 

 these tributary streams flow only after heayA' rain. The best 

 example is that to the south-Avest of the main granodiorite out- 

 crcip. This small stream has been formed/ along the junction of 

 the basalt, and the granodiorite. At its junction Avith Deep Creek 

 there is a fall 80 ft. in height. OAA'ing to their poor supply of 

 Avater the tributary streams are unal^le to corrode their beds as 

 rapidly as the main streams. This is the chief cause of the lack 

 of adjustment betAveen the tributaries and the main streams in 

 this area. At Hanging Valley (see Z, Plate XXXII.), this lack of • 

 adjustment is increased by the hard compact hornfels in its lower- 

 course. 



Deserted Bed of Jachsons Creek. — An old accumulation of 

 boulders can be seen in the right bank of the Maribyrnong River, 

 a quarter of a mile south of the junction of the creeks. Some of 

 the boulders are huge, some small, some of basalt, some of con- 

 glomerate, and others of sandstone, but none of granodiorite. 

 It Avas the old bed of Jackson's Creek Avhich deserted it Avhen it 

 floAved 6 ft. above its present level. If Deep Creek had contri- 

 buted boulders to the conglomerate, granodiorite also Avould have- 

 been represented. 



