January 14, 



.] 



SCIENCE. 



57 



sive plains descend toward the Atlantic, 

 famous since Darwin's voyage, are ac- 

 counted for as sea cliffs, cut during the re- 

 covery from a period of depression after the 

 valleys had been eroded. Volcanic cones 

 and lava flows give some variety to the re- 

 gion. Salt lakes are barred in valleys be- 

 hind the sand reefs of the former shore lines, 

 and their salt is explained as having been 

 retained since a part of the ocean was there 

 enclosed. This conclusion, as well as the 

 implication that salt lakes are usually sup- 

 plied by salt springs, seems open to question; 

 but as a whole the geographical descriptions 

 are much more lucid than those that one 

 usually meets in geographical magazines. 



THE ST. CEOIX DALLES, MINN. 



A THESIS by C. p. Berkey, University of 

 Minnesota, discusses the ' Geology of the 

 St. Croix Dalles ' {Amer. GeoL, XX., 1897, 

 345-383) and throws much light on the 

 geography of the district, which seems to 

 be one of special interest. Cambrian strata 

 lying unconformably on pre-Cambrian ig- 

 neous masses constitute the bed-rock of the 

 region. Heavy glacial deposits, morainic 

 and washed, overspread the bed-rock and 

 determine much of the surface form. Large 

 glacial rivers and the discharge of the glacial 

 West Superior lake have carved important 

 valleys, of which the rock- walled dalles at- 

 tract most attention. Several abandoned 

 river-courses contain lakes, some of which 

 seem to belong in the rare species of pools 

 excavated by the plunge of extinct falls. 



SURFACE CUEEENTS OF THE NOETH SEA. 



Observations made for the Fishery Board 

 of Scotland on the surface currents of the 

 North Sea, chiefly by means of floating bot- 

 tles, are discussed by T. W. Fulton (Seat. 

 Geogr. Mag., XIII., 1897, 636-645). A tol- 

 erably regular circulation around the mar- 

 gin of the sea is found at an average rate 

 of two or three miles a day, southward on 

 the west, northward on the east side of the 



sea. The velocity varies with the winds, 

 and after a period of unusual and persist- 

 ent southeasterly winds in December, 1896, 

 and January, 1897, the current was re- 

 versed along the coast of Great Britain. 

 The currents are, therefore, ascribed to the 

 prevailing westerly winds, which drive the 

 water towards the eastern side of the sea 

 and tend to heap it up there. In the firths 

 the currents are irregular, varying with 

 winds and tides. 



"W. M. Davis. 

 Harvard University. 



CURRENT NOTES ON ANTHROPOLOGY. 

 THE UNITY OF THE HUMAN SPECIES. 



Little is now written about ' monogen- 

 ism ' or ' polygenism.' To the physical 

 anthropologist that question is quite ab- 

 sorbed in the wider one of ' variation.' But 

 the psychical unity of the species is still 

 lacking definition. A noteworthy contri- 

 bution to it is one by the Marquis de 

 Nadaillac in the Revue des Questions Scien- 

 tifiques for October last. He points out the 

 unending similarities in implements, arts, 

 funeral rites and religious symbols in tribes 

 of like stages of culture in all times and 

 places. 



That these are proofs of psychic identity 

 there can be no doubt. But it is not quite 

 clear how the author interprets them. In 

 some passages he speaks of such customs 

 and inventions being ' handed down from 

 unknown ancestors by generation to genera- 

 tion;' while elsewhere he says the solution 

 lies ' in the identity of the mind of man in 

 all periods and in all regions.' The latter 

 is the position which is most acceptable to 

 the trained ethnologist. 



local ethnographic collections. 



In the rapid changes of American history 



the mode of life of one generation is scarcely 



known to that which follows it. Hence the 



value of collecting, while we can, those ob- 



