46 Harris and Crawford: 



(c) They were in turn captured from the Glendoon by 



an eastern tributary of Cataract Gully, to form with 



this tributary the present Pyrete Creek, the erosive 



. power of the Glendoon having been considerably 



lessened by the Mount Gisborne lava field. 



The following classification of streams may be interesting. In 



preparing it the authors have had the benefit of Mr. R. A. Keble's 



-co-operation, and have also used his paper on Lava Residuals. 8 



Pre-Newer Basalt. - (a) Pre-Djerriwarrli - Bullengarook (infilled). 



Cycle Fault Eastern and western sub-bas- 



altic streams and tributa- 

 ries (infilled), 

 (b) Post-Djerriwarrk - Upper Jackson's Creek (re- 

 Fault versed portion of Bullen* 

 garook (infilled). 

 Djerriwarrh. 

 Gleudoon. 



Slocombe's (infilled). 

 Upper Pyrete (originally flow- 

 ing north). 

 Several infilled streams. 



Newer Basalt Cycle Many streams obliterated by 



successive lava flows. 



Post-Newer Basalt ------ Goodman's Creek. 



Cycle Cataract Gully. 



South-west reach of Pyrete. 

 Jackson's Creek. 

 Riddell's Creek. 

 All streams on Newer Basalt. 



VI. — Lower Ordovician. 



(a) Distribution and Fossils. 



Lower Ordovician rocks were found only to the west of the 

 Djerriwarrh fault. They comprise sandstones, slates and shales 

 and differ little in appearance from rocks of similar age in other 

 parts of Victoria. The prevailing strike seems to be slightly 

 east of north, as compared with a strike of slightly west of north 

 in the Bendigo, Castlemaine and Daylesford districts. The 

 easterly strike, however, prevails in the more southerly Steig- 

 litz area. The predominance of sandstones, the covering of sur- 

 face soil, the almost entire absence of artificial sections, and a 

 .troublesome cleavage, render the delimitation of graptolite zones 



