Vol. XXVII. 

 1910 



1 Armitage, Country about West Essendon. S9 



grains vv^ere present in the substance of the pebble ; so these 

 pebbles were evidently clay before their inclusion in the grit 

 beds. At first sight they might be taken for small water-worn 

 pebbles of Older Basalt included in the grit beds while fresh, 

 and then weathered to wackenite. They remind one of the 

 formation of similar pebbles from clay derived from Older Basalt, 

 which is to be seen proceeding, for example, on the seashore near 

 Anglesea at the present day. The clay bed near the bottom 

 of the Pits was also probably derived from decomposed Older 

 Basalt, although there is a possibility of its origin being decom- 

 posed felspars of a neighbouring granite. 



Peculiar pipe-like concretions, in some cases many feet in 

 length, are to be seen in the face of the open cut. These look 

 like branches of trees which have become fossilized ; but careful 

 examination gives no trace of plant structure. In one case, what 

 appeared to be cell structure was, on closer investigation, found 

 ,to be really a kind of fur of small aggregates of radiating 

 crystallites of iron oxide. Many of the concretions are com- 

 pletely or partially filled with various forms of stalactitic limonite. 

 At present there is no evidence to connect these pipe-like con- 

 cretions with fossil wood. The weathering-out of these pipes 

 causes hollows to form in the face of the open cut. High up 

 these are utilized by sparrows and starlings, and lower down by 

 rabbits. Mr. D. G. Peele, the manager of the company which 

 works the deposits, who very kindly pointed out many features 

 of interest, and also gave much valuable information, states that 

 originally some of these holes were tenanted by wombats. The 

 sharp, angular, coarse sand of these beds is much sought after 

 for building purposes, the iron present with it, when combined 

 with the builder's lime, causing it to make a very good cement. 

 It is being largely used in the construction of the new bridge 

 over the Saltwater River at Maribyrnong-road. The very fine 

 sand at the top of the beds is, so Mr. Peele states, used not only 

 in Victoria, but is exported to New South Wales and Tasmania. 

 It is eminently suitable, on account of its fineness and evenness, 

 for brass-moulders' work. In fine weather the quantity of 

 building sand taken out from the Pits and screened averages 

 100 tons a day. As the deposit is not very extensive, it will 

 readily be appreciated that before many years have passed away 

 this interesting geological section will also have disappeared. 



With regard to the probable source of the material of the 

 Sand Pits and of the quartzites which will be presently described, 

 and whose original ingredients have been derived from the same 

 source as those of the Pits, Mr. (now Dr.) Hall and Mr. Pritchard 

 (10) write : — " Silurian rocks have probably yielded the greater 

 part of the Tertiary sediments [of the Melbourne district]. In 

 places, however, the sand grains are large and roughened, so 



