GEOLOGY. 213 



formation, without the slightest indication of a great subsequent 

 subsidence, seems to me the most complete and direct demonstra- 

 tion of my proposition. Of the western part of the continent I am 

 not prepared to speak with the same confidence. Moreover, the po- 

 sition of the cretaceous and tertiary along the low grounds east of 

 the Alleghany range is another indication of the permanence of 

 the ocean trough, on the margin of which these more recent beds 

 have been formed. I am well aware that, within a comparatively 

 recent period, portions of Canada and the United States which now 

 stand 600 or 700 feet above the level of the sea have been under 

 water; but this has not changed the configuration of the conti- 

 nent, if we admit that the latter is in reality circumscribed by the 

 200-fathoin curve. 



" Geologists have appealed very freely to oceanic currents as 

 accounting for the presence of loose materials upon the surface of 

 the earth. But now that the actual mode of distribution of 

 such loose materials under the action of extensive and powerful 

 currents begins to be known, those who explain the facts in this 

 way are bound to show that their arrangement actually agrees 

 with the effects of oceanic currents. I must confess that I have 

 looked in vain in the trough of the Gulf Stream for traces of the 

 characteristic mud which pours from the mouth of the Amazon 

 in quantities sufficient to discolor the water of the ocean for a 

 great distance from shore ; and yet the equatorial current of the 

 Atlantic is one of the greatest and most powerful of all known 

 currents. 



"Another side of this subject is also immediately connected with 

 deep-sea soundings. Geologists, and especially those of the 

 school of Lyell, have again and again assumed the slow rising of 

 extensive tracts of land from beneath the water, and taken all 

 sorts of loose materials irregularly scattered over the surface of 

 the land as evidence of its former submersion. But since the 

 dredge has been applied to the exploration of the deep, and a 

 great variety of animals, in a profusion rivalling that of shoal 

 water, have been brought up, 'not only from the immediate vicin- 

 ity of the land, but at various distances in increasing depth from 

 one to two, and even many hundred fathoms, no observer is justified 

 in considering extensive deposits of loose materials as marine in 

 which no traces of marine organic remains are found. The very 

 mud and sand of the deep teem with innumerable microscopic 

 living beings, the solid parts of which are easily detected in the 

 smallest samples of marine deposits, and may therefore afford a 

 satisfactory test where larger animals or plants are wanting. 

 Now, after surveying the whole width of our western prairies 

 without finding anywhere a sign of marine animals or plants, I 

 cannot see that there is any evidence of their marine origin, or of 

 the influence of oceanic currents in accumulating or distributing 

 the loose materials scattered over those vast plains. On the. other 

 hand, I have ascertained that the foundation rock upon which 

 these materials rest is everywhere polished, grooved, and scratched 

 in the same characteristic manner as the well-known glaciated 

 surfaces, wherever exposed. I have seen such polished rocks in 



