Gold in British Guiana. 273 
salt, have forms almost as invariable as simple crys- 
tallized substances. In the Canary Islands and in 
the mountains of Auvergne, in Bohemia, in Mexico, 
and on the banks of the Ganges, the formation of trap is 
indicated by a symmetrical disposition of the mountains, 
by truncated cones, sometimes insulated, sometimes 
grouped, and by elevated plains both extremities of which 
are crowned by a conical rising." In striking contrast 
are the moderate heights and gently swelling eminences 
of the older Palaeozoic rocks, which give rise bv denuda- 
tion to the rounded outlines which miners are accustomed 
to attribute to metalliferous districts generally. A closer 
examination reveals that "blunt cones with craters indi- 
cate volcanoes, a series of peaks like a saw denotes 
dolomites, rounded heads like the tops of nails charac- 
terise calcareous rocks, triangular points slates or quartzi- 
ferous schists, needles crystalline schists, capricious 
twistings and crumplings serpentines and trachytes, pyra- 
midal forms phonolites, etc., thin and dark looking walls 
intimate the presence of basalts, trachytes or traps. 
Rocks broken up by the weather into rounded masses are 
granites or grits or more rarely traps. ° 
It would be beyond the scope of this paper to refer in 
detail to the physical aspects of nature in the interior ; it 
is sufficient to remark that the mountain scenery is 
magnificent in the extreme, and the following description 
conveys but a faint idea of its surpassing beauty. "This 
beautiful park of nature is quite surrounded by lofty hills 
all arrayed in superbest garb of trees ; some are in the 
form of pyramids, others like sugar-loaves, towering one 
above the other, some rounded off, and others as though 
they had lost their apex. Here two hills rise up in spiral 
