62 
THE GEOLOGIST. 
years and ten, has laboured for inconceivable millions of years in the 
fashioning and perfecting of our world — even the senseless winds 
and waters seem to hare joined in effort with the other more subtle 
powers in the general progress and elaboration of its structure. 
Deep down below, covered by a thousand feet of stone — so modem 
borings have taught us — are the ancient mountain ridges of the primitive 
■world. Deep down below, in their mysterious plutonism, are the 
crystalline primordial granites, and stacked above them are the ponder- 
ous stony records of the past creations and ages. Deep down below, 
and far back into time, must the mind by perception penetrate when it 
begins to study the order of the rocks ; and, without inculcating some- 
thing of the knowledge of the regularity of their succession, and the 
catastrophes by which that succession has been variously interrupted 
at particular times and places, how could we hope, when we opened and 
read from the great historical folios of those creations, which for ever 
have passed away, that our words would be intelligible or understood ? 
Much as is known of the rocks themselves, much yet remains to be 
discovered : there are wide fields yet to be trodden, wide gaps in our 
investigations yet to be filled up. Theories and systems are after all but 
the exposition of the existing knowledge of the time, and the prevalent 
ideas of one age have been deemed to be folly and ignorance in another. 
Men's inferences may have changed, but the facts remain ; and every 
year is bringing us nearer and nearer to the truth, however far we may 
be, notwithstanding all our advance, from a full knowledge of all the 
laws of nature. Those laws have ever been the same, before even the 
great foundation-stone was laid on which the superstructure of the 
fossiliferous rocks has since been raised. 
All soils or earths — rocks, as they are technically called — are divided 
into two classes or groups ; the one stratified or in layers (strata) and 
mechanically deposited by water from the degradation or waste of pre- 
existing mineral substances ; the other igneous, that is fire- formed or 
fire-altered, such as volcanic lavas and granite. An intermediate class, 
the metamorphic, is produced where the former or aqueous beds have 
been brought into contact with the latter — the heat of the one having 
changed the characters of the other — in the vicinity of, and often to 
some considerable distance from, the point of junction. The heat has 
also destroyed or obliterated, to a greater or less degree, the traces of 
organized fossils. 
