20 P. A. ØYEN [1914 



tektoniske forhold, og »the salient feature in this seeming con- 

 fusion is the predominance of folds« (The Geographical Journal, 

 London, 1894, pag. 367); men man finder dog her ogsaa paa 

 den anden side fremhævet, at »with regard to the features im- 

 pressed by the action of running water, a great contrast exists 

 between the two slopes. Towards France, where denudation has 

 been more aclive, and especially at the Atlantic end, where the 

 rainfall is greatest, transverse valleys are the rule, while to the 

 south most of the rivers in part foUow the direction of longi- 

 tudinal folds, the valleys in some cases retaining the original 

 form of the latter« (L. c, pag. 367). Af de i orografisk og geo- 

 logisk hensende vigtige undersøkelser, som den russiske geolog 

 Obrucheff har utført, viser det sig, at > Central Mongolia is 

 intersected by many chains of mountains and hills, always having 

 the direction of either west-north-west or north-east. They are 

 separated from each other by broad depressions, having the 

 characters of either longitudinal valleys or flat depressions, en- 

 closed on all sides bj' mountains. A characterislic fea- 

 ture of the ridges of Central Mongolia (also of East Mongolia 

 and North-Western Nan-shan) is, that they all stand on broad 

 pedestals which sometimes reach one half or two thirds of their 

 relative heights above the depressions. These pedestals have soft, 

 smooth outlines, while what rises above them is always rocky 

 and divided into broken, ragged peaks. This feature (whatever 

 its cause may be) is general, but in some ridges it is especially 

 well pronounced« (L. c. 1895, pag. 263). Og om forholdene ved 

 Kuen lun uttales: »The chains and valleys are due to a might}^ 

 erosion; there are no »tectonic« longitudinal valleys, and the 

 rivers flow in transversal valleys, eroded across the ridges « (L. 

 c, pag. 265). Og med hensyn til forholdenes utvikling i vort 

 eget land er det jo af interesse at erindre, at selv Kjerulks egen 

 elev, Brogger, uttalte ved en senere anledning: »Die heutige 

 Oberflåchenform zeight nåmlich, dass die Erosion durch Weg- 

 fiihrung ungeheurer Massen des Felsenkorpers die jetst charak- 



teristischen Profillinien der Thåler etc. geliefert haben 



und es ist ganz sicher nicht correct, zu schliesen, dass die wahren 

 Ziige des Oberflåchenreliefs »auf ein Werk denten, das au.s einem 

 einzigen Stauungsprocess resultiren k6nnte< « (Nyt Mag. for Na- 

 turvid., B. 28, pag. 414 — 415). Naar vi saa erindrer Kjerulfs 

 hele syn paa de orografiske forhold, saa er det vanskelig at 

 finde modsætningen i dette tilfælde skarpere fremhævet, ja som 

 vi ser endog henpekt særlig paa en bestemt uttalelse (Kjerulf: 

 Udsigt over det sydlige Norges geologi, 1879, pag. 262), og det 

 tiltrods for at Brogger like iforveien har uttalt, > dass Verwer- 

 fungen eine ausserordentlich durchgreifende Bedeutung fiir die 



