238 Scientific Intelligence. 



No. 226. — Boundaries of the United States and of the several 

 States and Territories; by Henry Gannett, 138 pp., 54 pis. 

 The usefulness of this manual is shown by the fact that two pre- 

 vious editions have been exhausted. The history of all important 

 changes of territory is given, together with a copy of the laws 

 concerning them. 



No. 229. — The Tin Deposits of the York Region, Alaska; by 

 Arthur J. Collier, 57 pp., 1 pis., 5 figs. Tin ore probably of 

 commercial value has been found in widely separated localities 

 in the York region. The ore occurs in alluvial deposits occasion- 

 ally traced to small veinlets in slate, and in well-defined veins of 

 greisen associated with siliceous intrusions. Mr. Collier gives a 

 valuable general discussion of the occurrence and method of 

 working tin, and adds a bibliography of the subject. 



No. 230. — A Gazetteer of Delaware; by Henry Gannett, 

 15 pp. 



No. 231. — A Gazetteer of Maryland; by Henry Gannett, 

 84 pp. 



Folios. No. 101. — San Louis Folio, California, by H. W. Fair- 

 banks. The Coast Ranges of California are exceedingly com- 

 plex in their geologic structure and students will welcome this 

 description of a typical area. The sedimentary rocks represented 

 belong to Jura-trias, Cretaceous, Neocene and Pleistocene forma- 

 tions, and the igneous rocks, both extrusive and intrusive, date 

 from these same periods except the Pleistocene, and there is in 

 addition a pre-Triassic granite. The igneous varieties repre- 

 sented are granite, diabase, basalt, augite-teschenite, olivine- 

 diabase, quartz-basalt, rhyolite, tuff, pyroxene-andesite, peridotite, 

 pyroxenite, norite, gabbro, andesite-granophyre and dacite-gra- 

 nophyre. The Jura-trias rocks contain molluscan remains not 

 found elsewhere on the Pacific coast. Lens-shaped bodies of 

 jasper occur with the sandstone, and there is an abrupt change 

 from the rock containing siliceous tests of radiolaria to the 

 shallow water formation showing no radiolaria. Abrupt altera- 

 tions of currents, or depth, or shore line, must have taken place. 

 Lenticles of glaucophane schist from 1 foot to 100 feet in thick- 

 ness are irregularly formed and ascribed to contact metamor- 

 phism. The volcanic eruptions connected with the Monterey 

 shale (Neocene) occurred beneath the sea and consist largely of 

 ash and pumice. The pumice has become so impregnated with 

 pyrite as to form a very resistant rock in which shore terraces 

 are cut. In its topographic development this region presents an 

 interesting study of planation, stream adjustment and of devel- 

 opment of a coast line during several periods of elevation and 

 depression. The San Louis valley has been developed by two 

 sets of tributary streams, while the master stream crosses the 

 valley at right angles and enters a canyon. The Salinas is an 

 excellent example of a superimposed stream. It flows in a 

 granite-walled canyon parallel with and a short distance from a 

 wide valley cut in soft rock. Numerous faults are described by 



