Geohxjy of Broddineadoivs. 167 



These sediments clearly underlie the newer basalt, and are 

 therefore older. 



Ascending the right branch of the Moonee Ponds Creek the 

 first of the newer rocks to be found in contaot with the silurian 

 is, omitting the sub older basaltic clay previously discussed, 

 the older basalt in a decomposed condition, showing platy struc- 

 ture and spheroidal weathering. Immediately following this is an 

 outcrop of quartzites which appear to come down to the level of 

 the Silurian. Then 50 yards or so further on, the older basalt 

 comes in again in the columnar quarry. In one place on the 

 side of the valley the older basalt appears vertically above the 

 quartzite. We must therefore consider two possibilities: — 

 (1). Quartzites, etc., older than the older basalt. 

 (2). Quartzites, etc., newer than the older basalt. 



(1). That this was probably the conclusion of the officers of the 

 Geological Survey is evident from the index on the quarter 

 sheet. Tlie quartzites, etc., are called '"older pliocene," and the 

 older bagalt " pliocene '" simply. R. A. F. Murray, in his 

 Geology of Victoria (6), has referred to the existence of quartzites 

 underlying the older basalt, but does not give examples. 



This theory involves the likelihood that all the quartzites, 

 grits and sands are not of the same age, for the unconsolidated 

 sands occur at a much higher level than any part of the older 

 basalt, and immediately underneath the newer basalt. It would 

 enable us to read the section in the bed of the creek above the 

 quarry with more confidence as a sub older basaltic tertiary 

 bed, and therefore as a non-silicified part of the same series as 

 the quartzites. 



The evidence is chiefly the apparent vertical distribution of 

 the older basalt above the quartzites. 



(2). In this case the quartzites are read as resting on a differ- 

 entially eroded surface of older basalt, and any apparent con- 

 tradiction occurs where the quartzite is not in situ and has 

 suffered hill slip. All the quartzites, grits' and sands can then 

 be taken as belonging to one series, or two conformable series. 

 This view receives all the support of correlative evidence. 

 ' Lithologically this series is similar to the series of quartzites 

 and grits and sands of West Essendon (10), which rests uncon- 

 formably on the older basalt (10). Mr. R. W. Armitage records 



