ON THE ORIGIN AND FORMATION OF COAL. 27 



formation of coal as to the manner in which the alterations of stratification in 

 coal-fields were caused; but, as this covers nearly all known geological science, 

 we will not attempt to give it in full. We may concisely state that all these theo- 

 ries contain elementary facts ; that perhaps all the above causes cited may have 

 had a part in the formation of coal, but that we cannot take any one theory and 

 bring all the facts of coal formation deposits within the area of its hypothesis. 



Ever since the existence of coal formations have been demonstrated to exist 

 within several degrees north of the Arctic circle ; that coal measures and accom- 

 panying fossils are found north of 66° of north latitude; that the existence of 

 lignite beds in Greenland, Iceland and Spitzbergen, on Mackenzie river, in 

 Alaska and in the circumpolar lands north of Behring's Straits, another difficulty 

 has been added to the previous perplexing questions involved in the explanation 

 of the formation and deposit of coal. 



This is the question of terrestial temperature then and now, and how to 

 account for the anomalies involved by the existing present state of the globe 

 compared to its former state, when, from fossil evidence, we find palms, magno- 

 lias, pines, redwood, sassafras, sweet-gum and other trees growing formerly in 

 Greenland, Spitzbergen and Iceland, when we find fossil shells and corals that 

 require 66° mean sea temperature, now fossil on the Arctic sea-shore, and derived 

 from carboniferous strata. These instances, and the direct proof that far within 

 the Arctic circle once roamed vast herds of elephants, mastodons and wild horses, 

 with animals akin to our buffalo, deer, musk oxen and domestic oxen, proves 

 beyond doubt a change as vast in temperature as in animal and vegetable 

 creation. 



So, then, if we adopt Prof. Dana's theory of the presence in the water and 

 atmosphere of an excess of carbonic acid and carbonic acid gas ; that we, per- 

 haps, in the Devonian and Carboniferous Ages had then a greater measure of 

 internal heat from the as yet unadjusted and balanced cooling of the external 

 crust of the earth ; that the low elevation of the then dry land, the prevalence of 

 vast sheets of fresh water in shallow lakes, the presence of and the tempering 

 influence of great seas had a very material part in stimulating plant-growth ; that 

 their preservation and transformation into coal was aided by the presence, then, 

 of great quantities of rich hydro-carbons, and the continuance, for untold ages, 

 of this condition finally resulted in our present coal beds and coal measures. 

 Willing, perhaps, to accept these as good, probable causes for the deposit of all 

 coal measures known, yet this theory does not give us full conviction, as it asks us 

 to accept tacitly a condition of terrestrial and atmospheric differences incompatible 

 with our present known data of temperature, latitude and the seasons. In other 

 words, it seems to ask our full belief in a past condition of things terrestrial, in- 

 compatible with all present known laws from which we must derive some points 

 of analogy and comparison, asking us to accept the idea of an almost universal 

 average of sub-tropical temperature as ruling the earth from the Devonian until 

 the end of the Tertiary, and that, too, far within the Arctic circle, with no ex- 

 planation of such assumption. 



