(jeobxjn of Lihi<liile. 34y 



c. Tilt- Loiitr Ddctite. Serie.'<: — 



This series is associated with its successor. " 'I'he Middle Dat ite 

 .Series," {d), by strong affinities, Avhicli pL'ue the pair in sharp eon 

 trast with the first series, (a and />). whiih are also closely affiliated. 



This series is characterised by al)uiidant phenocrysts of ipiartz. 

 and some of felspar and biotite, all set in a glassy to crypocrystal- 

 Jine ground mass. The series consists chiefly of lavas, charged with 

 fragments of this and other igneous material, and of hornfels. In 

 the weathered sections, exposed along the railway line l)etween Lily- 

 dale and Evelyn, this included material is well exhibited. Tlie 

 fragments vary from the smallest size to that of a man's head. All 

 •this points to an alteiiiation of explosive and effusive phases, I'esult- 

 ing in the incorporation In- the lava flows of showers of fragments. 



Towards the close of the series the effusive phases disappeared, 

 and it finished with a facies that is entirely fragmeutal. These 

 rocks are best developed between Montrose and Evelyn on four lofty 

 a-idges, which run out fi-om the main Dandenong Range northwards 

 towards Olinda Creek. They vary from a coarse agglomerate to 

 ■dun-coloured lapilli, containing no visil)le mineials. The latter 

 •occur always higher up than the foi-mer, and were probably tlie 

 Jast phase of the series. For convenience, these fragnientals are 

 referred to as "The Dandenong Agglomerates." (Plate XXX., 

 Fig. 2.) 



Close to the place where the Evelyn fault crosses Olinda Creek, 

 the upper part of this fragmental series has been faulted down to 

 stream level, and there tlie agghmieiate is very coarse. One frag- 

 jnent measured fully 12 in. in diam.. and it and others were more 

 rounded than angular. There is little doubt that this place marks 

 a centre of eruption. This is rendered still more likely Ijy the 

 proximity of the hornfels, fragments of which are so numerous in 

 the effusive facies of this series. This site is marked as a volcanio 

 centre on the map. 



Stratigrnphiral Felnf ion ships. — The Lower Dacite Series may 

 be seen in a hill secrion about A mile south-east of Lilydale. Allot 

 292, superposed on the Upper Toscanite Series, (6), and containing 

 numerous fragments of the latter near the junction. It is. there- 

 fore, younger than (h). (See Plate XXX.. Fig. 1.) 



If anyone starts from Olinda Creek to climb the noith flank of 

 Mt. Dandenong, he will pass up in order over the following rocks : 

 — (1) The Lower Dacite Series, finishing with the fragmental rocks 

 named above, "the Dandenong Agglomerates"; next, (2V the 



