292 On the Boulders of Primitive Rocks found in Ohio, fyc. 



is the inclination to indolence, that a plausible theory is likely 

 to be preferred to a laborious investigation of facts, and to 

 render the person adopting as well as the one inventing it, 

 satisfied and contented, with so cheap and easy substitute for 

 knowledge. I doubt also the soundness of these " specula- 

 tive conjectures," and the force of these " irresistible impres- 

 sions," and incline to think them altogether visionary. 



The question how the boulders of primitive and transition 

 rocks, found scattered over the north western territory, came 

 there, can be answered, only when many facts, of which, 

 as yet, we are entirely ignorant, are discovered and pro- 

 ved. The composition of these boulders may be similar 

 to, or identical with the composition of some primitive and 

 transition formation known to exist, in situ, in such relative 

 position, as would admit of removal to the places where the 

 boulders are now found, by the application of an adequate 

 force. That such force could have existed and have been 

 applied, consistently with the known laws of nature, must 

 also be established. 



McKenzie and Bigsby are not the only writers from whom 

 we learn, that a ridge or mountain range, of primitive and 

 transition formation, extends from the coast of Labrador to 

 the north west of Lake Superior, dividing the waters which 

 fall into Hudson's Bay, from those which fall into the lakes 

 of the St. Lawrence ; but, whether this is a continuous and 

 unbroken ridge, seems doubtful. It may however be admit- 

 ted as probable, and it may also be probable, that it contains 

 all the varieties exhibited in the composition of the boulders 

 in question, and yet these probabilities would be but a weak 

 substratum whereon to erect a scientific edifice. 



I do not pretend to have seen more than a small part of 

 these boulders, and the portion which I have examined is 

 much smaller. The northern ridge I have never seen, nor 

 have I access to any geological description of it. The boul- 

 ders which I have examined, are granite, gneiss, sienite, and 

 greenstone ; of granite and granitic aggregates every variety 

 mentioned by Cleaveland, except graphic granite. Fine spe- 

 cimens of a porphyritic granite, apparently identical with 

 that described by Doct. Bigsby in the Journal of Science, 

 vol. 8, p. 65, are found near Columbus, Ohio. The gneiss 

 also embraces many varieties, some of which alternate with 

 hornblende slate, and some contain the common garnet; 

 there is also a considerable variety in the sienite. Almost all 

 the greenstones which I have seen, were situated in the val- 



