612 



SCIENCE 



[N. S. Vol. XLIX. No. 1278 



Professor H. H. Chapman returns to the 

 Yale Forest School to assume Ms duties as 

 Harriman professor of forest management. 

 He has been assistant district forester, in 

 charge of silviculture at Albuquerque for the 

 past two years. 



At the recent commencement the following 

 appointments were made in the department of 

 zoology, college of liberal arts, Syracuse Uni- 

 versity: Dwight E. Minnich, Ph.D. (Harvard, 

 '17), of Oxford, O., instructor in zoology; 

 Harry S. Pizer, M.Sc, of Brooklyn, K T., as- 

 sistant in zoology. 



De. Frank A. Haktman, of the department 

 of physiology, the University of Toronto, has 

 been appointed head of the department of 

 physiology at the University of Buffalo. 



■Colonel J. G. Ajdami, F.R.S., professor of 

 pathology, McGill University, Montreal, has 

 been elected vice-chancellor of the university 

 in succession to Sir Albert Dale. 



Professor Grafton Elliot Smith, pro- 

 fessor of anatomy in the University of Man- 

 chester, has been appointed to the chair of 

 anatomy at University College, London. 



DISCUSSION AND CORRESPONDENCE 



TECTONIC FORM OF THE CONTINENTS 



Our prevailing notion concerning conti- 

 nental mass is strictly geographic in signijB.- 

 cance. In our definition tectonics finds no 

 place. Relation of sea and land is made causal 

 and essential ; whereas it is only accidental and 

 trivial. The outstanding feature is a broad 

 basin with high mountainous rim and a low 

 sea-level interior. This is a sitatement of the 

 observation of the late Professor J. D. Dana. 

 In its larger, or telluric, aspects this definition 

 is genetically without meaning. 



In the final analysis of the major relief fea- 

 tures of our globe the hydrosphere is for sim- 

 plicity's sake left out of account. The effect 

 then is as if the entire face of the earth were 

 a land area. A condition is premised anal- 

 ogous to that of our waterless moon. Genet- 

 ically the oceans serve only to obscure the 

 tectonic essentials of relief expression. 



Recent experimental reproductions, in sphe- 

 roidal masses, of those broad basinal tracts that 

 correspond to the oceanic depressions of the 

 geoid are accompanied by results having 

 curious significance. They point to the fact 

 that we shall have to modify our basic concep- 

 tions concerning all the major deformations 

 of the earth's crust. 



Instead of distinguishing between continen- 

 tal elevations and oceanic depressions, a cir- 

 cumstance imposed by an unweening impor- 

 tance attached to the presence of the sea, a no- 

 tion handed down from time immemorial, the 

 proper discrimination to be made is between 

 the cordilleran ridges of the continental bord- 

 ers and the intervening lowlands, whether 

 above the level of the waters in the continental 

 interiors, or beneath sea-level in the oceanic 

 areas. On this basis the tracts which we are 

 accustomed to designate the oceanic depressions 

 and the sea-level interiors of the continents are 

 arranged in the same taxonomic category. 

 Consideration of any such datum plane as sea- 

 level may be with full propriety entirely neg- 

 lected. The meridional disiwsition of the con- 

 tinents thus comes to be readjusted as rela- 

 tively narrow orographic ridges in place of 

 broad basin-'Shaped plateaus. 



The tectonic consideration of a waterless 

 earth casts a new light upon the schematic 

 form of our globe. In its logical consequences 

 the contractional hypothesis finds expression 

 in isudh figments of the imagination as the 

 reseau pentagonal of Elie de Beaumont, and 

 the tetrahedral globe of Lothian Green. To 

 be sure the form known as the tetrahedron is 

 of all geometric solids the one form which 

 possesses the least volume in comparison with 

 a given surface area, while the sphere contains 

 the greatest bulk within the same surface; yet 

 the collapse of the latter is not necessarily a 

 ciystaliographic shape as that indicated by the 

 former. 



In the present state of our knowledge any 

 schematic form of our earth is largely conjec- 

 tural. However, it is suggested lately that in 

 the case of a collapsing spheroid the initial 

 tendency towards a faceted form would prob- 



