JANUAET 8, 1915] 



SCIENCE 



51 



ordinary circumstances, and yet may be 

 clearly detected and their intensity and 

 duration measured by a seismograph. 

 Every earthquake indicates a change in 

 the relative position of the rocks, however 

 small, either horizontal or vertical or both, 

 and consequently in the relief of the coun- 

 try. It may truly be said that the moun- 

 tains are growing. In no other part of the 

 United States is there as great seismic activ- 

 ity as along our Pacific coast, a fact which 

 means that the mountains are not only 

 growing, but growing faster than elsewhere 

 in the United States. Some are growing 

 less, others greater, and there is need, as 

 pointed out by Lawson, of establishing 

 bench marks on opposite sides along the 

 faults, so that the amount and character of 

 the change may be measured. 



The transformation of the Sierra Nevada 

 from a region of low relief to one of high 

 relief so increased the river grades of its 

 western slope that they have carved out 

 deep canyons which now form the principal 

 relief feature in the scenic attractions of 

 the range. The Tosemite Valley is the 

 finest example, although rivaled by that 

 of Kern River, and is one of our most im- 

 pressive and instructive national parks. 

 This is especially the case since nature has 

 made some of the finest trees in the region 

 big in proportion, as if to correspond to the 

 size of the canyon. 



KLAMATH MOUNTAINS 



The Klamath Mountains are an irregular 

 haK erescentic group of peaks and ridges 

 along the coast in northwest California 

 and southwest Oregon. The general shape 

 is that of a saddler's knife, with the 

 curved side to the west and the handle to 

 the east, a little south of the center. Their 

 greatest extent north and south is about 

 225 miles, with 75 to 115 miles in width. 

 The erescentic border follows the coast for 



about 90 miles north from the mouth of 

 Klamath River in California to near Rogue 

 River in Oregon. To the northwest of the 

 Klamath Mountains is the coast range of 

 Oregon. To the southwest is the coast 

 range of California, both overlapping the 

 western curve of the Klamath Mountains 

 along the coast. On the east lies the Rogue 

 River Valley, Shasta Valley and Sacra- 

 mento Valley bordered by the great lava 

 field of the Cascade range. 



The Klamath Mountains are composed 

 chiefly of Carboniferous and Devonian 

 sediments, with a large proportion of con- 

 temporaneous lava flows of rather basic 

 types. Besides these there are large bodies 

 of mica and hornblende schists of pre- 

 Paleozoic age, as well as sediments and 

 eifusives belonging to the Jurassic and 

 Triassic. 



These rocks are folded, faulted and in- 

 truded by batholithic masses composed of 

 granodiorite, gabbro and peridotitic rocks 

 centering in a general core with aligned ter- 

 minals that curve to the northeast in 

 Oregon and southeast in California. The 

 later sedimentary rocks of the Klamath 

 Mountains, the Jurassic and Triassic, are 

 richly fossiliferous in the Redding quad- 

 rangle, where they are associated with 

 equally fossiliferous Carboniferous and 

 Devonian strata that form the hills lying 

 east of the Sacramento River and the rail- 

 road between Redding and Mt. Shasta. In 

 the southern part of this exposure the Me- 

 sozoic rocks strike S. 50° E. in line with 

 rocks of essentially the same age and posi- 

 tion 75 miles away in the northern portion 

 of the Sierra Nevada. To the northward 

 in the Redding quadrangle we see these 

 Mesozoic rocks curve to the right and strike 

 to the northeast in the general direction of 

 the Blue Mountains of Oregon. Now this 

 change in the strike is not limited to the 

 eastern portion of the Klamath Mountains 



