CHAPTER XXXV. 
TEETIAET. 
LOWER (MIOCENE?) AND UPPER (PLIOCENE?) VOLCANIC ROCKS AND 
DRIFTS. 
RUSSELL RIVER AND MULGRAVE GOLD FIELDS, MOUNT MORGAN GOLD MINE. 
The presence of Tertiary rocks in Queensland is rather inferred than proved. 
To begin with, it is in the highest degree unlikely that this epoch passed over in 
Queensland without any deposition of either fresh-wator or marine strata, such as 
exist in all the noighbourning colonies. The absence, so far as we know for certain, of 
Tertiary marine strata may be due to the fact that the elevation which took place after 
the deposition of the U])per Cretaceous (Desert Sandstone) rocks placed the whole of 
Queensland above the reach of the ocean during Tertiary times. But in that case we 
should expect a widespread accumulation of fresh-water deposits. 
Daintree, indeed, who describes the Desert Sandstone as “ without doubt the 
most recent, widely-spread stratified deposit developed in Queensland,” and correctly 
observed that it lies unconformably on the Cretaceous Rocks of the “ Rolling Downs,” 
classed the Desert Sandstone as “ Cainozoic,” adding “ all that can be asserted is that 
its horizon is above and uneonformable to the Cretaceous Series of the Flinders.” As 
will be seen in the Chapter relating to the Desert Sandstone, that Formation must be 
regarded as Upper Cretaceous, the idea of its“ Cainozoic” age being no longer tenable. 
There is reason to believe that the Tertiary epoch was marked by intense 
volcanic activity, accompanying or following extensive movements of elevation. It 
may be well at the outset to glance at the history of volcanic activity in the other 
colonies in Tertiary times before considering whether Queensland affords any evidence 
of similar activity. 
In Victoria, according to Mr. Reginald A. F. Murray, Glovernment Geologist,* 
the Eocene of Europe has no Victorian representative. “ I'he Victorian Lower Tertiary 
beds, which the term Oligoccne has been employed to designate, really belong to the upper- 
most portion of the Lower Tertiary group, and appear to occupy an intermediate 
position between the Eocene and Miocene.” These consist exclusively of marine 
deposits. 
The Middle Tertiary (Miocene) is extensively developed in Victoria. It 
comprises “ deposits due to marine, lacustrine, and fluviatile agencies, and also the rocks 
of igneous origin, classed as Older Volcanic, which appear to be the youngest of the 
group, and to form the division between beds of Middle Tertiary and Miocene and 
those of Upper Tertiary or Pliocene age.” 
“The Older Volcanic rocks are the latest products, and mark distinctly the close 
of the Middle Tertiary or Miocene era. There do occur, occasionally, thin volcanic 
layers, iuterstratified with the Miocene sedimentary beds, showing that vulcanicity was 
not altogether dormant during the formation of the latter, but the greatest volcanic 
activity evidently took place at the close of the period. Where undecomposed, the 
Older Volcanic basalts are usually dark, dense, and solid, of a polygonally jointed and 
* Geology and Physical Geography of Victoria. Melbourne : by Authority : 1887. 
