June 28, 1907] 



SCIENCE 



1011 



far, before the thrust, B, would take up all the 

 stress. 



There is no obvious reason to limit the 

 development of the schuppenstruktur, A and 

 Bj to two thrusts. A third and possibly a 

 fourth might be produced. It might, how- 

 ever, occur that the accumulated thickness of 

 piled-up strata should become so great, or the 

 conditions of slight resistance in the plane of 

 shear so favorable to displacement, that the 

 whole recumbent mass would move forward 

 upon a great major thrust, C, to an indefinite 

 distance. 



It is apparent on inspection of the diagrams 

 that the length of the strata involved in the 

 recumbent folds between M and N bears a 

 relation to the total displacement on the over- 

 thrusts. The two are not equal, for the strata 

 in the overturned limbs of the recumbent 

 folds are stretched; but the two lengths may 

 be said to be of the same order of magnitude. 



The preceding hypothetical relations of re- 

 cumbent folds to overthrusts were developed 

 from a study of the extraordinary recumbent 

 folds of Mont Joly as described by Hitter.' It 

 followed from measurement of Eitter's sec- 

 tions that the length of strata involved in the 

 recumbent folds was about 130 kilometers, 

 whereas that included in the supposed roots 

 was but 16 kilometers. If the folds and roots 

 bear the relations attributed to them the 

 lengths of the strata when developed should 

 be at least of the same order of magnitude. 

 The further analysis of the problem led to the 

 conclusion that the recumbent folds represent 

 a sequence of thrusts, as described above. 

 The probable total displacement on thrust 

 planes might he as much as 80 kilometers. 

 The present position of the thrust planes 

 would be above the Alps, or in the alpine 

 summits, on the assumption that they have 

 been raised during later elevation of the 

 range. Their extent would carry them over 

 the range to the southern slope. 



At first sight this conclusion appears to ac- 

 cord closely with the phenomenal nappes des 

 recouvrement of Lugeon, but there is a dis- 



' ' La bordure sud-ouest du Mont Blane,' Bull, 

 des Serv. de la carte de la France, No. 60, profile 

 I., Plato I. 



tinction. Whereas the nappes are supposed 

 to have been projected over the Alps at their 

 present elevation, the thrusts are believed to 

 have developed in a shear zone beneath the 

 surface, before the Alps were the visible 

 mountains of to-day, and to have risen from 

 a considerable' depth toward the surface, as 

 is the habit of thrusts. On independent evi- 

 dence the date of thrusting is assigned to a 

 pre-Eocene (pre-Flysch) date. The elevation 

 which has raised the fully developed, one 

 might say exhausted and dissected, thrust 

 planes to the height of the summits of the 

 Alps is, on the other hand, assigned to the 

 middle Tertiary epoch of diastrophism, which 

 also caused folding and the more obvious over- 

 thrusting. Bailey Willis 

 U. S. Geological Sxtkvey 



QUOTATIONS 



teachers' salaries and MINNESOTA 



There has been recently among the alumni 

 in various eastern colleges and universities, 

 notably of Harvard and Princeton, a move- 

 ment to secure funds to advance the salaries 

 of instructors. The movement has appealed 

 with some success to the loyalty of alumni 

 and the benevolence of interested friends. A 

 similar movement was actively started among 

 the alumni of the University of Minnesota 

 last fall, with the result that the regents of the 

 university now have at their disposal an 

 annual appropriation of $165,000, made by the 

 legislature of the state, available for current 

 expenses. Salaries of instructors have al- 

 ready been materially advanced in some cases 

 to a level which places the University of 

 Minnesota in active competition with the lead- 

 ing universities of the country so far as the 

 compensation of its instructors is concerned. 

 This must be regarded as a very important 

 advance in the development of state universi- 

 ties. Its economic importance as bearing 

 upon the general problem of the compensa- 

 tion of teachers is even greater, for the alumni 

 of Minnesota appealed not only to loyalty and 

 benevolence, but to a legislature responsible 

 for the proper support of the first educational 

 institution in its state. They carried through 



