Geology ot Broadmeddows. 163 



that it contains abundant material of what in the field appears 

 undoubtedly fossil wood, but which on examination in the labora- 

 tory does not disclose cell structure. The cell, structure may 

 have been destroyed during the replacement of the organic 

 material by limonite. 



In the bed of the creek upstream from the quarry, decomposed 

 older basalt may be seen above a clay containing" quartz grit, 

 which passes into a bed of more or less re-sorted kaolinised 

 granitic material containing some white to brown mica. This in 

 turn passes into a white clay. The observations are made in 

 plan and are not too clear, and admit of two explanations. 

 First that here, the only point in the district, we have an outcrop 

 of a bed which may possibly be correlated with the lower tertiary 

 leaf beds which underlie the older basalt at Royal Park (4) and 

 elsewhere. Secondly, that the resorted granitic material is but 

 a thickened part of the 2-foot bed observed lower down, which 

 has not been so deeply ironstained, and that this in turn, rests 

 on a clay Avhich is part of the silurian series. 



Distribution and General Characters of the Older Basalt. 



The older basalt occurs in an oblong-shaped area of undu- 

 lating country to the west of Gellibrand Hill, and along the 

 valley of the right branch of the Moonee Ponds Creek, in 

 Sections VII., Will Will Rook, and XV. and XVI., Tullamarine. 



The occurrence is the most northerly extension of the series 

 which is found in Green Gully, Keilor, along the Saltwater at 

 .Sunshine, at Essendon, Moonee Ponds, Flemington and Royal 

 Park. It is exposed on the hillsides and along the bed of the 

 creek, but is best studied in some river cliff sections and in a 

 •quarry in the southern portion of the area. In this quarry the 

 rock is perfectly fresh and shows a remarkably good columnar 

 structure. The columns are best seen on the southern wall of 

 the quarry, where they are well marked, though not so straight 

 and clean cut as the newer basalt columns, known as the "' Organ 

 Pipes,'' near Sydenham ; nor are they as high, being not more 

 than 20 feet. On opposite walls of the quarry they are tilted in 

 directions towards one another. On the N.W. face the columns 

 iire tilted at about 40 deg. to the vertical and at a much smaller 



