MACKIE — THE GEOLOGY OF THE SEA. 
243 
with present and historically recorded influences, so admirably and 
widely propagated by the philosophical Lycll, has undoubtedly been 
carried to the exti'eme by unreflecting votaries of our science, in the 
attempt to identify the phenomena of remote geological ages with 
those going on nuw around us. As in chemistry, there are two ways 
of determining the composition of a substance — analysis and syn- 
thesis — the taking to pieces and the putting together, so in nature 
there are universally two ways in which physical influences may 
operate — separation and combination. One substance liberated by 
chemical action under one condition may combine with another sub- 
stance in another condition, and a third element may thus be 
liberated which might bring another influence into play fi'om which 
other combinations and other liberations would follow, so that in the 
endless changes which are capable of thus being eflected, we might in 
the lapse of time find Nature still adhering to fundamental physical 
laws, but working in quite an opposite, or at any rate a very 
difierent, manner, to the identity thoughtlessly or in the heat of 
enthusiasm anticipated or presumed. 
But to return to our first question. Was it the briny ocean that 
ebbed and flowed around the primordeal gneissic island-tracts, and 
washed and triturated the sand- granules and clay-atoms of the 
" Bottom-rocks," which formed theii' strands ? 
To set methodically to work to answer this we must begin at the 
beginning ; we must get, if we can, at some idea of what the first 
crust of the globe was hke, and what first produced the sea. One 
man of high note as a geologist and chemist has done something for 
us on the first point. Mr. S terry- Hunt, a gentleman connected with 
the Geological Survey of Canada — a country where the greatest 
development of those old primitive rocks is displayed — has made use 
of the opportunities of his vocation to investigate the chemical con- 
ditions of those most ancient known strata, and has given us as a 
conclusion of his researches, that in the primitive crust of our planet 
" all the alkalis, lime, and magnesia must have existed in combina- 
tion with silica (quartz) and alumina (clay), forming a mixture which, 
perhaps, resembled dolerite, while the very dense atmosphere would 
contain in the form of acid-gases all the carbon, chlorine, and sul- 
phur, with an excess of oxygen, nitrogen, and watery vapour." These 
