252 SEE— FURTHER RESEARCHES ON [April 24, 



the leakage of the oceans, to which mountain formation is due. Of 

 course the plasticity of this layer beneath the crust contributes to 

 the final result, but the leakage of the oceans, with the resulting 

 earthquakes, supplies the deforming force. 



§ 46. Viezi*s of Professor Suess. — In the " Face of the Earth " 

 (Vol. I, p. 107) we find the following brief exposition of Professor 

 Suess' views : 



" The dislocations visible in ihe rocky crust of the earth are the result 

 of movements zvhich are produced by a decrease in the volume of our planet. 

 The tensions resulting from this process show a tendency to resolve them- 

 selves into tangential and radial components, and thus into horizontal {i. e., 

 thrusting and folding), and into vertical {i. e., sinking) movements. Dis- 

 locations may therefore be divided into two main groups, of which one is 

 produced by the more or less horizontal, the other by the more or less 

 vertical relative displacement of larger or smaller portions of the earth's 

 crust. 



" There are large areas in which the first, and others in which the 

 second group predominates, and there are also regions in which both groups 

 appear together, and in which an intimate connection may be recognized 

 between them, the resolution of the movements in space having in these 

 cases been less complete. This essential difference in the movements of the 

 lithosphere may be clearly perceived from a comparative study of the struc- 

 ture of the Old World; nor has it escaped the notice of American 

 geologists. 



" ' The geological provinces of the Great Basin,' remarks Clarence King, 

 has suffered two different types of dynamic action : one in which the chief 

 factor was evidently tangential compression, which resulted in contraction 

 and plication, presumably in post-Jurassic time; the other of strictly verti- 

 cal action, presumably within the Tertiary, in which there are few evidences 

 or traces of tangential compression.' 



" Our colleagues on the other side of the ocean have even gone a great 

 deal further. After comparison of the folded Appalachian mountains with 

 the depressed Basin Ranges, Gilbert had in 1875 already suggested the 

 possibility that in the Appalachians the causes of movement were superficial, 

 in the Basin Ranges deep-seated. We shall have an opportunity, when dis- 

 cussing the relation of the Alps to their northern foreland, of determining 

 to what extent this supposition finds confirmation in Europe. We may how- 

 ever state at once that as a rule it is only the dislocations of the second 

 group which are accompanied by volcanic eruptions." 



§ 47. Vieivs of Arrhenius. — It is well known that this distin- 

 guished Swedish physicist holds that the earth's interior is essen- 

 tially gaseous (cf. §45, above), but under the great pressure oper- 

 ating in the globe made to behave very nearly as a solid. ^ In his 



' See Postscript, page 274. 



