IxXXviii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



matter is here and there vomited forth in fusion, or blown out of 

 vents by the discharge of vapours and gases, and large tracts of 

 the solid surface of the earth are violently shaken, and portions of 

 land raised or depressed. We also know that at the present, slow 

 changes in the relative levels of sea and land are being eifected. 

 Thus from our own experience and from the study of what has 

 formerly happened, we find that the surface of our planet is and has 

 been, during the lapse of such geological time as we can trace, in an 

 unquiet state. AVe of course know nothing of the height to which 

 the crushing or elevating of rocks into mountain-chains may have 

 forced mineral accumulations, though we may often infer that very 

 great heights are but the remains of rocks, the removed portions of 

 which rose still further into the atmosphere ; but, taking the Hima- 

 layan chain as the highest land, we have nothing rising six miles 

 above the sea-level. If we increase this height to ten miles, we should 

 still have an insignificant fraction of the earth's radius. 



The researches of Mr. Hopkins lead him to infer that at present 

 the solid crust of the earth cannot be less than 800 to 1000 miles 

 thick. Supposing this to be so, the hypothesis of a cooling globe 

 would give a less thickness in past geological times, one gradually 

 diminishing to the early period when solid matter could be first 

 formed. I need scarcely call your attention to the view which has 

 been taken of the forcing-up of mountain-chains, and the unequal 

 tilting and adjustment of masses of the surface to accommodate the 

 crust to the still fluid mass beneath, as cooling proceeded. Neither 

 need I speak of the effects which would follow from the action of the 

 heated and still fluid mass upon the portions of the fragments which 

 may have descended different depths into its surface, or of the intru- 

 sion of the molten matter amid the broken masses; we have only to 

 inquire how far these breakings-up and squeezings of the previously 

 solid crust at different times is likely to have interfered materially 

 with its general uniformity, so that any important change in the 

 earth's axis, with its geological consequences, may have resulted. 



As regards the mineral matter thrust up into the atmosphere, we 

 see that, as soon as this is effected, it is attacked along the sea-level 

 by the breakers, and both on coasts and inland by atmospheric in- 

 fluences, all tending to lower the altitude of the mass so elevated, 

 and to carry its component parts into the sea, filling up any inequalities 

 which may have been formed beneath it, in consequence of this 

 surface-movement of the rocks. It is during this removal of mineral 

 matter and its spread in various directions, that the remains of the 

 animal and vegetable life of succeeding geological times become 

 entombed, adding, and in many instances most materially, to the 

 masses accumulated in various ways upon the previously moved rocks. 

 This action therefore tends to plane down the unequal surface above 

 the sea and fill up inequalities in its bed. While this proceeded, 

 we should expect that the heated matter beneath would also melt 

 down any portions of the solid masses, squeezed and forced into it 

 by these movements, to a distance from the surface corresponding 

 with the general heat of the globe at the time, and therefore the 



