PHYSICAL FEATURES OF THE REGION. lo 



graphical area, but the collections of Chestnut and Drew a indicate 

 that it may be phytologically distinct from the section west of the 

 South Fork Mountains. A collection of plants, including several 

 grasses, has been made by Miss EasUvood during the summer of 1901. 



7. The Siskiyou, Scott, and Salmon mountains. Collections of 

 grasses from this region were made by Mr. T. H. Gilbert in the sum- 

 mer of 1899 and Mr. H. P. Chandler in the summer of 1901, but have 

 not yet been completely worked up. 



Only the first four of these subdivisions are discussed in the present 

 report. On account of the brevity of the flowering season of grasses 

 in California, of the extent of the region included within the above- 

 described boundaries, and of its general inaccessibility and the cost 

 of travel in a mountainous and thinly populated country, it was found 

 impossible to visit all of the subdivisions of the region. Those por- 

 tions most prominently devoted to dairying and cattle raising were 

 therefore selected for investigation. They include a large portion of 

 Mendocino and Humboldt counties and the narrow strip of coast line 

 in Del Norte County. 



These three are the most northerly coast counties of California, and 

 together cover an area of about 8,513 square miles. On the accom- 

 panying map (I) their position is indicated by the dotted portion, 

 the heavy lines nearest to it on the east and south marking the 

 inland boundaries of the whole region of northwestern California. 



TOPOGRAPHY. 



In a paper on the " Geomorphogeny of the coast of northern Cali- 

 fornia, 11 Prof. A. C. Lawson says of the topography of Sonoma, Mendo- 

 cino, and Humboldt counties: 



The coast ranges of northern California comprise, besides the mountains proper, 

 which, except for isolated peaks, are distant from the ocean, a broad coastal tract 

 which may be said to be devoid of true mountain topography. This tract is 

 clearly a dissected plateau . and impresses itself as such upon the observer very 

 forcibly when viewed from any point not lower than its general level. (See 

 Plate I.) The plateau is now represented only by long, roughly level-topped 

 ridges, which are separated from one another by long, narrow valleys. At the 

 heads of the streams which drain the valleys the ridges are frequently confluent. 

 The ridges have a remarkable constancy of general altitude. The observer 

 stationed on one which is slightly more commanding than the rest beholds a vast 

 expanse of country, with no prominent profile against the sky throughout the 

 tract in Sonoma and Mendocino counties. Ridge succeeds ridge in seemingly 

 endless sequence, and to an observer overlooking the foreground the general effect 

 of the ridges falling away in perspective is that of a plain. So situated he can 

 easily imagine the intervening valleys filled flush with the crests. The plain so 

 restored would be neither level nor even. It would be a sloping plateau of low 

 relief. Along the front of this plateau, where it overlooks the ocean, its general 



a Drew, Elmer R. Notes on the Botany of Humboldt County, Cal.: Bui. Torr. 

 Bot. Club, XVI, 147-152. 1889. 



b Lawson, Prof. A. C. ; Geomorphogeny of the coast of northern California: Uni- 

 versity of California, Dept. of Geology, Bui— 241-272, Nov. 1894. 



