266 K W. Hilgard — Old Tertiary of the Southwest. 



as yet unspecialized sensations, accustomed to a dusky day of 

 a few brief hours succeeded by as short a night. The moon — 

 perhaps much nearer and of ampler but paler disk — speeding 

 through its phases in the quick period of a week or less. The 

 sun — of enormously greater volume than we behold it — diffus- 

 ing its hazy beams, and probably expending a much smaller 

 amount of radiant light and heat upon the flat and dreary face 

 of nature than it now does after many hundred million years 

 of waste.* Such is the outline of early meteorological condi- 

 tions which the geologist should take into his account when 

 theorizing on the grand dynamics of his science. 



But of that primeval period of fleeting days and of shortened 

 axis, perhaps the only physical record and memorial left us is 

 the wide array of distorted crumplings and ruptured foldings 

 (culminating apparently in the lower or middle latitudes) which 

 have formed the needful condition and environment for man's 

 advancement, and which have never ceased to excite the won- 

 der and admiration of his observant and inquiring intelligence. 



Art. XXXIIL— The Old Tertiary of the Southwest; by E. W. 



Hilgard. 



In an article published in the June and July numbers of this 

 Journal, Dr. Otto Meyer undertakes to show, not only that 

 numerous supposed species of fossils heretofore described from 

 the Tertiary of the southwestern States should be canceled as 

 being mere variations of no specific value, but also that there 

 is good reason to suppose that the stratigraphic succession of 

 the several stages, as heretofore understood and accepted, is 

 incorrect and actually requires to be turned upside down. As 

 regards the former part of his thesis I thoroughly agree with, 

 him, if not in detail at least in the general issue. As regards 

 his second point, it is simply incorrect ; and it is difficult to 

 understand how, if Dr. Meyer took the pains to do more than 

 look over the lists of fossils in my report on the geology of 

 Mississippi, he could entertain such a proposition for a moment. 

 The only explanation of his error can be found in the fact, 

 evident from the whole of his article, that he is unacquainted 

 with the methods of field geologists, and imagines that the 

 paleontologist is the final arbiter in all questions of geological 

 age. There was a time when this idea was current even among 

 geologists ; but at least on this side of the Atlantic it has for a 

 number of years counted among the "uberwundene Siaiidpunkte." 



* It is well known to physicists that radiation is not in proportion to tempera- 

 ture. The "lime-light " radiates a far greater amount both of heat and of light 

 than the simple oxy-hydrogen flame at a higher temperature. 



