MACKIE — THE GEOLOGY OF THE SEA. 



243 



witli present and historically recorded influences, so admirably and 

 widely propagated by tbe pMlosopliical Lyell, lias undoubtedly been 

 carried to the extreme by um-eflecting votaries of our science, in the 

 attempt to identify the phenomena of remote geological ages with 

 those going on noiv around us. As in chemistry, there are two ways 

 of determining the composition of a substance — analysis and sijn- 

 thesis — the taking to pieces and the putting together, so in nature 

 there are universally two ways in which physical influences may 

 operate — sejjaration and comhination. 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 from 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 

 laivs, 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. 



BuL'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 a.nd clay- atoms of the 

 " Bottom-rocks," which formed their 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 like, 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 Ihe greatest 

 development of those old primitive rocks is displa^yed — ^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 



