-50 Harris and Crawford: 



The distribution of the beds shows that the country between 

 Slocombe's Corner and Goodman's Creek forms the arch of a 

 geanticline. This is represented diagrammatically in Fig. 1. The 

 prevailing dip in the east is westerly, apparently owing to in- 

 version, as the Upper Ordovician rocks appear to dip below 

 the Lower Ordovician. The sequence of graptolites denotes a 

 prevailing northerly pitch. This may be partly due to faulting, 

 in which case it would be necessary to assume a down-throw 

 to the north or opposite to that of the larger faults further south. 

 It is both possible and probable that faults, of which we have 

 no knowledge, are responsible for the meagre development of 

 Middle Castlemaine and Victoria Gully beds. 



VII.— Upper Ordovician. 



(a) Distribution and Fossils. 



On the Quartersheets Upper and Lower Ordovician are both 

 included in the Lower Silurian, but Upper -graptolites are re- 

 corded by Sir F. McCoy from Ba 64 15 (on Jackson's Creek near 

 the mouth of Evans Creek), and from Ba 67 16 (at the junction 

 of Riddell's and Jackson's Creeks). With the recognition of 

 Darriwil graptolites at Macedon the east boundary of the Lower 

 Ordovician was brought within six miles of known Upper Ordo- 

 vician beds. One of our tasks was to reduce this distance still 

 further. Our plan was to work down Jackson's Creek from Gis- 

 borne, but fortune- favoured us at the outset, as we discovered 

 Upper Ordovician graptolites in a " wash-out," or gulch, which 

 runs from the Mount Alexander Road to Jackson's Creek, at the 

 south-east of Gisborne township. This discovery pushed the 

 Upper Ordovician boundary about 30 miles west of the longi- 

 tude of Melbourne. 



The Upper Ordovician rocks consist of hard quartzose bands, 

 coarse and fine sandstones and shales. The shales range from 

 black and carbonaceous to a pipeclay-white, and, except in the 

 west of the area, are usually decomposed. All the Upper Ordo- 

 vician rocks have been subjected to great pressure, to which 

 they seem to have yielded more readily than the Lower Ordovi- 

 cian. The hardest bands are often contorted, and are sometimes 

 pinched out altogether. Slickensided faces are common. The 

 slates in the bed of the Djerriwarrh are traversed by thousands 



15. 1, Dec. 1, pp. 10-12. 



16. 1, Dec. 11, pp. 33, 34. 



