Post Tertiary. 
99 
system of deep leads of Creswick, Clunes, and Daylesford, on 
their trend towards the Murray. At Ballarat there are four and 
in other places two or three distinct layers of basalt covering the 
leads. 
The lowest overlie the deepest parts of the gutters, and the next 
in succession spread more widely till, as may now be seen, the 
uppermost lava-flow forms a wide sheet, covering not only the old 
rivers and their tributaries, but also most of the lower ridges of 
Silurian rock which separate them. 
Throughout all the Newer Volcanic areas are found the points 
of eruption whence the lava streams issued, mammaloid or conical 
hills in many of which well formed crater-basins still exist, while 
in others the crateriform shape is still distinguishable though the 
basin has been obliterated. Many of these extinct craters are now 
occupied by lakes or lagoons, as Tower Hill, near Warrnambool, 
which has an insular peak rising from the centre of the lake ; 
Mount Eels, and other crater basins in the Western District, and 
Mount Mercer, south from Buniuyong. Mounts Buuinyong, 
Warrenheip, Pisgah, Franklin, and numerous other volcanic hills 
in the Ballarat, Creswick, Daylesford, and other districts, are 
familiar instances of points of eruption where the outlines of the 
craters are still discernible. 
Around nearly all such points are scoriaceous lavas and volcanic 
ashes, among which are frequently found ejected masses of older 
rocks, from mere dust up to several tons in weight. 
For instance, in the volcanic asli of the Anakies, near Geelong, 
are found ejected blocks of granite. At Buuinyong and Hardie’s 
Hill, to the south thereof, are ash beds, composed principally of 
large and small fragments of slate and schist. In some places, as 
on the Werribee Plains, near Mount Mary, the ash beds present a 
stratified appearauee, as though their materials had fallen into and 
had been arranged by water. It is probable that this may have 
been the case, but there is no evidence of any very considerable 
submergence Hince, as, had such taken place, very few, if auy, of 
the volcanic hills, composed as they are of loose incoherent mate- 
rials, would have preserved their form as we now see them. It 
is probable, however, as suggested by Mr. Selwyn, that some of 
them formed low islands in the Tertiary seas. 
Post Tertiary. 
The Post Tertiary deposits, or those which have been formed 
since the Newer Volcanic lava flows, consist of gravels, clays, 
sands, mud, loam, &c., aud sometimes form very extensive tracts 
of good alluvial soil. 
They rest directly on the Palaeozoic or the Mesozoic rocks, or 
on Tertiary beds and volcanic layers, as the case may be. 
