±66 E. Blackwelder — Yakutat Coastal Plain of Alaska. 



They consist of many materials, usually poorly assorted, and 

 often imperfectly rounded. The minerals are not oxidized, 

 and carbonaceous material is abundant. Conglomerates are 

 interleaved with graywackes at many horizons. Ripple-marks 

 and cross-bedding are found in the coarser beds. Fossils are 

 very rare, and of those discovered the commonest may perhaps 

 be plant stems or worm trails. Only a single identifiable shell 

 has been found* and that not in this vicinity. There are even 

 beds suggestive of glacial action. f 



I interpret this to mean that, at a much earlier time, this 

 part of the Alaskan coast had much the same cool, rainy climate 

 that it has to-day, that it was bordered by a growing foreland 

 covered with dense vegetation and was backed by rugged 

 highlands 



Russell;}; describes a series of rocks, younger than the Yakutat 

 formation, which he found on the slopes of the St. Elias range 

 and named the Pinnacle series. This comprises 1800 feet of 

 dark gray sandstone and shale with beds of conglomerate. 

 Some of the beds contain marine shells ; others have coal seams. 

 Here again there is a lack of oxidation products and an alter- 

 nation of dark clastic sediments suggestive of the modern 

 coastal deposits. 



In one of the coarse conglomerates of the Yakutat series 

 I observed a bowlder, itself composed of an older conglomerate, 

 and among the pebbles in the latter were hard quartzitic gray- 

 wackes of the same unoxidized carbonaceous character. That 

 this represents a still earlier epoch of similar conditions is at 

 least suggested. 



Taken together, these facts seem to indicate that certain 

 climatic and physiographic conditions have recurred at widely 

 separated intervals in this single region. In each case the 

 record is purely sedimentary rather than paleontological. 



University of Wisconsin, March 1, 1909. 



*E. O. Ulrica, Harriman Alaska Exped. Kep., iv, pp. 125-148. 

 f Eliot Blackwelder, Jour, of Geol., xv, p. 11-14. The probable glacial 

 origin of certain folded slates in southern Alaska, 1 907. 

 % Loc. cit. p. 170-173. 



