MECHANICS OF FORMATION OF ARCUATE MOUNTAINS 



177 



The drawings upon which these figures are based have been 

 reproduced on a much reduced scale in Figs. 15 and 16. From 

 examination of them it is learned that an anticline within a com- 



FiG. 16. — Cosine areas of the underturned stages 7 to 9 of a growing anticline 

 (assuming, however, that the length of the arch is not increased). 



petent stratum is able in its early stages, when the ratio of rise to 

 span is relatively small, to lift but a small proportion of its load from 

 the underlying formation; but that this competency increases 

 beyond the arbitrary stage i, in which the ratio of rise to span 



