313 
tion and comparative freshness of the shells and corals, the 
emergence of Tasmania from the sea could not be assigned 
to many centuries. Indeed, the general aspect of the southern 
part of Australia indicates comparatively modern upheaval, 
at first rapidly and then somewhat slowly, but, probably, subject 
to periodical increased intensity in the subterranean forces, as 
observed on the coast of Chili. 
In the Bay of Panama, along the banks of the river Bayano, 
I have seen several terraces of marine beds, from the coast 
to about fifty feet above high-water mark, of comparatively 
recent origin. Since the town was built the upheaval has 
been sufficient to render the port worthless excepting for 
small boats and canoes. Hence the subterranean action is 
never at rest, and is constantly, although imperceptibly, rising 
or depressing the surface of the earth. The fundamental base 
of the dry land is composed of an aggregation of crystals, 
formed into masses of rocks of various degrees of compact- 
ness, from mere pasty consistency to the hardness of quartz, 
presenting various structures, from the compact granular to 
the laminated formations known by the names of granites, por- 
phyries, gneiss, and schistose rocks. 
The predominating crystals of which the fundamental base, 
or the primary rock, is composed, are quartz, felspar, mica, 
talc, hornblende, chlorite, schorl, carbonate of lime, sulphate 
of lime, fluor spar, &c., &c. Besides these conspicuous crys- 
tals there are also disseminated in the primary rocks, either 
in minute grains or in solution, all the known metals ; and 
these are often seen gradually developed by crystallization 
from their solvents in subterranean vacuities, caverns, mineral 
veins, &c., and the aggregated crystalline compound becomes 
active en masse. 
The crystals of which the primary rocks are composed could 
never be the production of incandescent matter, as they all 
require a certain proportion of water in combination for their 
formation, to which their transparency is in many instances 
referable. 
Thus, crystals of sulphate of lime are of a glossy trans- 
parency, and of regular figure : this is due to water ; heat 
them and they crumble into a white powder. Quartz 
contains from 5 to 20 per cent, of water; felspar from 3 to 10 
per cent. ; and many compounds as high as 45 per cent, of 
water. All the rocks, the most solid and compact, lose a large 
proportion of their weight on being exposed to the sun, and 
many decrepitate when exposed to strong heat: the weight thus 
lost being water. Indeed, there is scarcely a substance known 
but what is either found in solution, or may be dissolved in an 
