122 
Geology and Physical Geography : 
laminar quartz, the deposit proceeded slowly in successive coats* 
thus giving time for the associated deposit of the rarer minerals. 
Much of the finer free gold, in portions of lode above water- 
level, may have been originally in mechanical combination with 
pyrites which have since decomposed. 
With respect to the primal origin of the gold itself, it can be no 
better accounted for than can that of iron, lead, or any other metal 
or form of matter; but with regard to its association with the 
Palaeozoic rocks, there is an hypothesis available, the advancement 
of which can at least do no harm. The conjecture is based on 
the known presence of a minute proportion of gold in sea-water 
and it is supposed that when the Silurian rocks were being laid 
down, gold was present in the water in greater quantity than now; 
that much of it was gradually precipitated and deposited either 
free, or in chemical combinations, with the sediments as they slowly 
accumulated, and that after the consolidation and upheaval of the 
strata, permeating heated mineralized water, both of meteoric 
origin and incorporate 1 with the rocks, conveyed the gold in 
solution in company with the silica to the vein fissures, where it 
was segregated into grains, strings, and crystals, forming masses- 
of greater or less size, from invisible specks up to large nuggets, 
according to the intensity of the agencies at work. Premising 
with the remark that the theoretical views advanced are only given 
as a working hypothesis to he held with a loose grasp, and likely 
to be modified by new facts, Mr. A. W. Ilowitt, from whom I first 
acquired the idea, has generously placed at my disposal the follow- 
ing notes, which I quote vi extenso. 
“ 1. I assume the existence of gold in solution in the Palaeozoic 
seas. 
“ 2. The Silurian sediments, during their formation, necessarily 
included a large amount of sea-water (organic matter may have 
precipitated gold iu a metallic state, and in a finely-distributed 
condition, throughout and in these sediments). 
“ 3. This included sea-water could not escape until the sedi- 
ments were raised above sea-level. 
“ 4. The geological evidence shows that before being so raised 
they were folded, compressed, and depressed within the influence 
of the internal heat of the earth. (It is immaterial whence this 
heat was derived — possibly due to the molten interior, and heat 
resulting from motion iu the crushed sediments.) 
“ 5. The sediments were then invaded by molten rock masses 
from below; were metamorphosed, melted, and absorbed as to 
their lower portions; the molten material was forced upwards 
through the line of least resistance to the surface, and gave rise 
to the Palaeozoic volcanoes, e.g., of the Snowy River. The great 
masses of molten material on final consolidation are represented 
by the granitic rocks underlying all Victoria. 
