AMEEICAN GEOLOGY MACLUREAN ERA, 1785-1819. 211 



of their Transactions. He mentioned the occurrence of iron ore, 

 gypsum, calcareous petrifactions, red, slaty stones, soft clay, a white 



fossil substance, rock crystal, a curious annular stone, 

 thVDrift° n i79^ ,nof an d sixty-four specimens of some varieties of stone 



found on the shore of Lake Ontario. Discussing' this 

 last occurrence, he wrote: 



Now, it is almost impossible to believe that so great a variety of stones should be 

 naturally formed in one place and of the same species of earth. They must, there- 

 fore, have been conveyed there by some extraordinary means. I am inclined to 

 believe that this may have been effected by some mighty convulsion of nature, such 

 as an earthquake or eruption; and perhaps this vast lake may be considered as one 

 of those great fountains of the deep which were broken up when our earth was del- 

 uged with water, thereby producing that confusion and disorder in the composition 

 of its surface which evidently seems to exist. 



So far as I am aware, this is the first recognition of or attempt to 

 account for the glacial drift, although its glacial character was of 

 course undreamed of. 



It is perhaps not strange that, with the cosmogonists not yet fully 

 out of the field, the "many-sided" Franklin should have indulged in 

 theories relative to the earth's histoiT, nor that such were, at the time, 

 thought worthy of consideration. In 1788, in a letter 

 ThelTrS i788 k,in ' s to the Abb e Soulavie, he suggested that the earth may 

 not be solid to the core, but that the outer portion or 

 shell is floating, as it were, on an internal fluid more dense than any 

 solids of which we have knowledge. He was led to this view from 

 seeing at the base of one of the Derbyshire, England, mountains, 

 " oyster shells mixed in the stones,' 1 a condition of affairs indicating 

 an elevation of this portion of the land above the sea level and which 

 he conceived could not take place were the earth solid. He wrote: 



Thus the surface of the globe would be a shell, capable of being broken and dis- 

 ordered by any violent movements of the fluid on which it rested. And as air has 

 been compressed by art so as to be twice as dense as water, in which case if such 

 air and water could be contained in a strong glass vessel the air would be seen to 

 take the lowest place and the water to float above and upon it; and as we know not 

 yet the degree of density to which air may be compressed; and M. Ainontons calcu- 

 lated, that its density increasing as it approached the center in the same proportion 



as above the surface, it would be at the depth of leagues heavier than gold, 



possibly the dense fluid occupying the internal parts of the globe might be air com- 

 pressed. And as the force of expansion in dense air when heated is in proportion 

 to its density; this central air might afford another agent to move the surface, as well 

 as be of use in keeping alive the subterraneous fires; though as you observe, the 

 sudden rarefaction of water coming into contact with those fires may also be an agent 

 sufficiently strong for that purpose when acting between the incumbent earth and 

 the fluid on which it rests. 



If one might indulge imagination in supposing how such a globe was formed, 1 

 should enceive that all the elements in separate particles being originally mixed in 

 confusion and occupying a greater space, they would, as soon as the- Almighty fiat 

 ordained gravity or the mutual attraction of certain parts and the mutual repulsion 



