Lawson.] 



Coast of Northern California. 



243 



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 pro- 

 file against the sky, throughout the tract, in Sonoma and Mendocino 

 Counties. Ridge succeeds ridge in seemingly endless sequence, 

 and, if one overlooks the foreground, the general effect of the 

 ridges falling away in perspective is that of a plain. So stationed 

 he can easily imagine the intervening valleys filled flush with the 

 crests, and realize how aptly Cook's description of the New Jersey 

 highlands, quoted by Davis and Wood,* applies to this portion of 

 California, although the features here are on a larger scale. 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 altitude is about 1,600 feet. 

 Back from the coast where it passes into the higher and more 

 mountainous tract of central and eastern Mendocino Count}- it has 

 an elevation of about 2,100 feet. On entering Humboldt County 

 several sharp peaks rise abruptly above the general level of the 

 dissected plateau to altitudes of from 3,000 feet to 4,000 feet; but 

 remnants of plateaux clearly encircle these and give their middle 

 slopes a distinctly terraced aspect. It is evident that, northward of 

 the 40th parallel of latitude, the forces which effected the evolution 

 of the original plain had made but little headway as compared with 

 the coastal region to the south of the same line, or they had been 

 interrupted in their work by orogenic disturbances. The plain in 

 Humboldt County presents no broad expanse, as in Mendocino and 

 Sonoma Counties, but may be followed in between an open cluster 

 of mountain peaks and ridges. The present reconnaissance estab- 

 lishes the fact of its extension as far as the Bear River Ridge. It 

 doubtless extends up the coast, however, far beyond the limit set to 

 the exploration. 



That this great dissected plateau represents an ancient peneplain, 



*Geographic Development of Northern New Jersey, Proc. Bost. Soc. Nat. 

 Hist., Vol. XXIV, 1S89. 



