PARALLELISM OF EQUATOR WITH THE MEDITERRANEAN ZONE 83 



plain the folding of the earth's crust, replaces this by the theory that by 

 the diminution of the oblateness dependent on slower rotation the moun- 

 tain folding could be fully accounted for. Admitting, with Lord Kelvin 

 and Darwin,* that the axis of rotation and maximum inertia of the 

 earth may have moved to any amount, and noting that the highest 

 mountains in the Andes and Himalayas are near the tropics and apart 

 from the equator, he suggests as a mere speculation that if the pole may 

 have been in the remote past transferred to Bering strait, bringing 

 " Guyot's central zone of fracture " (that is, the Mediterranean zone) to 

 be the equator, the highest mountains would be brought much nearer 

 the equator. This could be " only a shifting of the mass of the earth 

 (so to speak) upon*an axis fixed in angular direction, with accompany- 

 ing shifting within its substance of the equatorial plane of oblateness." 

 That is, the obliquity of the ecliptic must remain unchanged. 



We may look for other indications that this zone inherits its manifold 

 peculiarities from its former equatorial position. 



1. It is at first curious that the great chain of the Aleutians is con- 

 centric with the proposed position of the pole. 



2. In the short distance between Scotland and the Mediterranean are : 

 (a) The Caledonian chains with the great overthrusts of Eribol, and folds 

 of this age are continued south to the Ardennes ; (6) the Variscan chains 

 with the great overthrusts of the Belgian coal fields, and folds of this 

 age are buried beneath the later Alps ; (c) the Armorican chains, and (d) 

 the Tertiary folds of the Alps and Apennines, the latter series represent- 

 ing a crustal shortening of 74 miles, according to Heim. All are thrust 

 northwardly. 



The sinking of the Mediterranean region and shrinkage beneath this 

 area seem incompetent to this work. 



The inadequacy of the escape of heat to explain all folding, so strongly 

 enforced by Fisher,f Dutton.J and many others, may be for the moment 

 admitted, § and we may review the list of possible causes of crustal short- 



* Darwin admits an excursion of the pole of 10 or 15 degrees, and suggests its standing over 

 Greenland to explain the Glacial period. This wandering would be by steps of two or three de- 

 grees, followed by an earthquake assisted adjustment to a figure of equilibrium. (G. H. Darwin : 

 On the influence of geological changes on the earth's axis of rotation. Phil. Trans. Roy. Soc, 

 vol. clxvii, part i, 1877, p. 271.) 



t Physics of the Earth's Crust, 1889, p. 255. 



t A criticism of the contractional hypothesis. Am. Jour. Sci., 3d series, vol. viii, 1874, p. 113. 



§ This argument, based on a solid sphere of uniform initial temperature, cooling by conduction 

 according to a constant law of conductivity derived from imperfect experiments at low pressure, 

 involves more, and more improbable assumptions than does the hypothesis that the interior of the 

 earth may consist of highly condensed gases at temperatures above their critical points, an hypoth- 

 esis first advanced by Franklin (Conjectures concerning the formation of the earth : Trans. Am. 

 Phil. Soc, vol. iii, p. 1) and developed by Ritter in a wonderfully acute and original mathematical 

 analysis (Untersuchungen iiber die Hoheder Atmosphere und die Konstitution gasformiger Welt- 



