Notices of Memoirs — B. Willis — Drift, Puget Sound. 555 



Josef Land basalts had cooled slowly in a fissure, we should expect 

 to find the central portion of the dyke richer in iron-oxide than the 

 margin. Professor Lawson has described two basic dykes from the 

 Kainy Lake region, where this is actually the case, and a more 

 striking illustration is seen in the Taberg iron-ore mass, described 

 by Sjogren and Tornebohm, where the marginal portion of an 

 eruptive mass about one square kilometre in area is formed of 

 olivine-h3'perite containing only small quantities of magnetite and 

 olivine, and this passes inward by gradual stages into a magnetite- 

 olivinite without plagioclase. 



In conclusion, it is asked whether the metallic iron, which occurs 

 as interstitial matter in some of the Greenland basalts, may not have 

 been formed by the reduction, by included organic matter, of the 

 iron-oxides previously concentrated by progressive crystallization. 



in. — Drift Phenomena of Puget Sound and their Interpretation.^ 

 By Bayley Willis. 



rilHE area from which the facts for this discussion were collected 

 X is the Tacoma quadrangle of the United States topographical 

 survey, comprising the district east and south of Seattle and Tacoma. 

 The major topographic features are the channels of the Sound and 

 the strictly homologous valleys now filled with alluvium. These 

 divide, and in some instances surround, plateau-like elevations 

 composed of stratified and unstratified drift that rise about 500 feet 

 above the sea. On the slopes of the adjacent foot hills of the Cascade 

 Eange, drift deposits occur up to and beyond 1,700 feet above the 

 sea. Various features of the Glacial-derived topography have been 

 traced out in detail, including characteristic till surfaces, morainic 

 zones, kames, and overwash plains. The distribution of these 

 features indicates that at least the latest Glacial advance was along 

 the valleys and channels of the Sound, and that glaciers rose above 

 and overflowed the margins of the plateaus. The materials of the 

 drift are to a large extent granite, and bear evidence of pi'olonged 

 water transportation. A distinct variety of till, containing numerous 

 erratics of Tertiary volcanic origin, was found in localities to which 

 it was probably brought from the local centre of glaciation. Mount 

 Kainier. The relation of these local Glacial deposits to the general 

 drift indicates that the prevailing drift phenomena were due to 

 glaciers which penetrated from the north as far south as the foot 

 hills of Mount Rainier, thirty miles south-east of Tacoma. 



The detailed examination of the various features of the drift 

 suggests the hypothesis that the channels of the Sound are the 

 hollows remaining after repeated Glacial occupation of a wide 

 valley formerly diversified by the valleys and ridges of Pre-Glacial 

 topography. In the course of repeated Glacial advance and retreat 

 the earlier divides were built upon and transformed into plateau-like 



^ Abstract of paper read before the British. Association, Section C (Geology), 

 Toronto, 1897. 



