674 



SCIENCE. 



[N. S. Vol. XV. No. 382. 



of Adams on the Grenville Series of Canada, 

 constitute a substantial step toward a more 

 precise knowledge of the real nature and origin 

 of the Archcean complex. The need of modern 

 analyses of typical unaltered sediments for 

 purposes of comparison with crystalline met- 

 amorphic rocks in these and similar investiga- 

 tions is rendered apparent. 



SEQUENCE OF VOLCANIC ROCKS. 



In a paper by Lawson and Palache on the 

 Berkeley Hills, California (BiiU. of the Dept. 

 of Geology, Univ. of Calif., Vol. 2, pp. 349-450, 

 1902), the microscopical petrography of a se- 

 ries of andesitic, basaltic and rhyolitic lavas is 

 described in detail. The most interesting petro- 

 logical feature brought out in their description, 

 however, is the remarkable fivefold repetition 

 of the eruption of andesite, basalt and rhyolite, 

 in the order named. As the authors cautiously 

 point out, the small size of the area considered 

 (less than six square miles) renders it possible 

 that the perfection of this periodicity is acci- 

 dental, but this commendable reserve does not 

 deprive the fact of its importance and signifi- 

 cance. The paper, as a whole, is a successful 

 attempt to present to students a detail of the 

 remarkably rich geological field which sur- 

 rounds the University of California. 



F. L. Eansome. 



THE ALASKA FUEL SUPPLY. 

 In closing his discussion of the coal re- 

 sources of Alaska, in Part III. of the Twenty- 

 second Annual Eeport of the United States 

 Geological Survey, now in press, Mr. Alfred 

 H. Brooks- adds some brief comments on the 

 other sources of fuel. In addition to coal, 

 he says, there are three possible sources of fuel 

 supply in Alaska, namely, timber, petroleum, 

 and peat; and of these, timber alone has been 

 utilized. Southeastern Alaska is heavily 

 forested and afl:ords ample wood for fuel. 

 Certain species of trees are found as far west 

 as Kadiak Island. Beyond Kadiak, to the 

 west and north, the coast-region of Alaska is 

 practically treeless. Some willows, and oc- 

 casionally spruce, are found in the sheltered 

 regions; but for the most part the coastal belt 

 is covered simply with moss, grass and low 



shrubs. This type of vegetation extends 

 northward to Point Barrow and thence east- 

 ward. The moss and grass-covered plains and 

 the rolling plains are called tundras, and are 

 found on the northern continental margins 

 encircling the globe. 



The interior of Alaska has usually a sufii- 

 cient supply of wood for ordinary purposes of 

 building and mining and for fuel. The 

 larger river valleys are often heavily forested 

 with spruce and other trees. On the Yukon, 

 near the international boundary, the timber 

 line is at about 3,000 feet; northward it de- 

 creases in elevation, and on the Koyukuk it is 

 about 2,500 feet. Still further to the north 

 and west it further decreases in altitude, and 

 on the Upper Kobuk the timber is said to be 

 limited to the floor of the largest river val- 

 leys. In the northern Arctic drainage reports 

 state that there is no timber except the wil- 

 lows, which however grow to considerable size. 

 The Kuskokwim, Sushitna and Copper rivers 

 all have timber basins. During the great in- 

 flux of population of the last three years, much 

 timber has been destroyed by flre in the dry 

 summer months. In the northwestern and 

 northern parts of the territory, from Norton 

 Bay around to the mouth of the McKenzie, 

 the shore was once abundantly supplied with 

 driftwood. The Eskimos, who have been 

 using this wood for generations, are very 

 economical in the matter of fuel, and, until 

 the coming of the white man, the probabilities 

 are that the driftwood was accumulated faster 

 than it was used. This driftwood is brought 

 down from the interior by the larger rivers, 

 whose banks are wooded. The cutting of the 

 wood along the banks of the Yukon has already 

 decreased the annual contribution of drift- 

 wood to northern Bering Sea. This, together 

 with the rapid exhaustion by the white man 

 of the supply which had accumulated in the 

 past, will soon cause the Eskimo as well as 

 the white man to be dependent on other 

 sources for fuel. The North Arctic Coast 

 eastward from Point Barrow, which is but 

 thinly populated by natives and seldom visited 

 by whites, has some driftwood. The possibil- 

 ities of using for fuel the thick growth of 

 vegetable matter which covers most of the 



