Vol. 



XXVII, 



I9I0 



1 Armitage, Plant Remains in Olivine-Basalt. 



27 



To these I am now enabled to add — Carbonized wood in Newer 

 Pliocene basalt. 



Description of the Occurrence of the Plant Remains. 



In December, 1909, a specimen of charred wood closely 

 adhering to a piece of bluestone was brought to me by Master 

 Henry Baker, a lad in my geology class at the Melbourne Con- 

 tinuation School. He stated that it had been handed to him by 

 his father, who is a workman employed at the Melbourne Cor- 

 poration Quarry, Clifton Hill. From this quarry, which is about 

 three miles north-east of Melbourne, a large amount of bluestone, 

 an olivine-basalt, is procured for street-making purposes. It is 

 also famous for the numerous beautiful secondary crystallized 

 minerals that have been procured at various times from it. 



I thought the specimen given to me so unique that I went out 

 to the quarry, and Mr. Peter Tait, the manager, kindly allowed 

 the workman, Mr. J. Davies, who had broken open the basalt 

 containing the plant remains, to indicate to me the spot where 

 the specimen had been procured. It was on the north side of 

 the quarry in the lower part of the lowest flow and about 120 

 feet from the surface of the uppermost and most recent flow. 

 The basalt in the immediate vicinity of that in which the specimen 

 was imprisoned is of a light-greyish-blue colour and very tough 

 and dense, except in parts right at the base of the flow, where its 

 structure becomes ropy and scoriaceous. SHces examined under 

 the microscope show it to be a fine-grained rock, consisting of 

 granular aggregates of olivine with many phenocrysts of the same 

 mineral, which include small grains of magnetite and ilmenite ; 

 lath-shaped crystals and microlites of a plagioclase felspar, pro- 

 bably andesine, are fluidally arranged and ophitically included in 

 a matrix of pale brown augite, which, with small grains of olivine, 

 augite, magnetite, and ilmenite, constitutes the ground mass of 

 the rock. 



The following is an analysis (16) of a sample of Melbourne 

 basalt : — 



SiO, ... ... ... ... 49.95 



A1,0, 



Fe,0, 



FeO' 



MgO 



CaO 



Na.O 



K,6 



H3O+ 



CO, 



Total 



18.51 

 6.42 

 5.18 

 6.36 

 8.80 



3-25 



0.68 



0.70 

 0.15 



100.00 



From examination petrologically and from chemical analysis 

 the rock proves to be an olivine-basalt. 



