I40 GEOLOGY [Chap. IX 



Letter 491 think probable, or at least possible : viz., that the greater part 

 of Europe has at times been elevated in some degree equably; 

 at other times it has all subsided equably ; and at other times 

 might all have been stationary ; and at other times it has 

 been subjected to various unequal movements, up and down, 

 as at present. 



Letter 492 To C. Lyell. 



Down, Dec. 4th [i860]. 

 It certainly seems to me safer to rely solely on the 

 slowness of ascertained up-and-down movement. But you 

 could argue length of probable time before the movement 

 became reversed, as in your letter. And might you not add 

 that over the whole world it would probably be admitted that 

 a larger area is now at rest than in movement? and this I 

 think would be a tolerably good reason for supposing long 

 intervals of rest. You might even adduce Europe, only 

 guarding yourself by saying that possibly (I will not say 

 probably, though my prejudices would lead me to say so) 

 Europe may at times have gone up and down all together. I 

 forget whether in a former letter you made a strong point of 

 upward movement being always interrupted by long periods 

 of rest. After writing to you, out of curiosity I glanced at 

 the early chapters in my Geology of South America, and the 

 areas of elevation on the E. and W. coasts are so vast, and 

 proofs of many successive periods of rest so striking, that 

 the evidence becomes to my mind striking. With regard 

 to the astronomical causes of change : in ancient days in 

 the Beagle when I reflected on the repeated great oscillations 

 of level on the very same area, and when I looked at the 

 symmetry of mountain chains over such vast spaces, I used 

 to conclude that the day would come when the slow change 

 of form in the semi-fluid matter beneath the crust would 

 be found to be the cause of volcanic action, and of all changes 

 of level. And the late discussion in the Atkenceum, 1 by Sir 

 H. James (though his letter seemed to me mighty poor, and 

 what Jukes wrote good), reminded me of this notion. In 



1 " On the Change of Climate in Different Regions of the Earth." 

 Letters from Sir Henry James, Col. R.E, Atheticeum, Aug. 25th, i860, 

 p. 256; Sept. 15th, p. 355 ; Sept. 29th, p. 415 ; Oct. 13th, p. 483. Also 

 letter from J. Beete Jukes, Local Director of the Geological Survey of 

 Ireland, loc. cit., Sept. 8th, p. 322; Oct. 6th, p. 451. 



