Gold in British Guiana. 285 
of its having formed the bed of a lake at no very remote 
period. That the tradition of the Lake Parirha was not 
destitute of some foundation in fa6l may be taken as 
beyond dispute, and over very wide areas in the interior 
of the colony we find traces of great changes having 
taken place in tertiary times, the replacements of water 
by land, and alterations in the river systems. 
In all the countries in the world where diamonds occur, 
they are accompanied by certain constants in nature, and in 
British Guiana such mineral associates as pebbles of blue 
and yellow quartz, jasper, cornelian, agates, Lydian stone, 
rock crystals, garnets, platinum, iron-ores, etc., are spe- 
cially abundant. The South African diamond fields have 
been described as consisting on the surface of shales 
and sandstones, which represent old deposits of mud and 
sand now hardened and altered, but originally thrown 
down as sediment in a vast fresh water lake. In some of 
the East Indian fields the diamondiferous gravels are 
interbedded with marl, in which are found certain 
molluscs still existing in the neighbouring ocean. The 
obje6l of these remarks is to dire6l attention to the proba- 
bility of diamonds existing in our great drift beds which 
lie between the base of the mountains of the interior and 
the alluvial lands of the sea coast. They are set down in 
the geological map of the colony as composed of sand 
and clay, but have only been very slightly examined in 
part, although Schomburgk commented on the similar 
occurrence of marl and suggested the possibility of their 
containing valuable deposits. In one instance with 
which I am acquainted, a diamond of considerable size 
and value was discovered in this formation, under rather 
peculiar conditions. It was found embedded in a limy 
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