1921] Smiley: Flora of the Sierra Nevada of California 5 



carrying- abundant mica, as on the northeast side of AVard Peak. In 

 the region between the upper Tuolumne and the headwaters of Kings 

 River, slate forms the summits of man}' of the higher peaks, as Mt. 

 Lyell, and covers a considerable area west of the Sierra crest in the 

 high mountains of Fresno County. Mt. Goddard and peaks to the 

 west are of slate. ^ In the southern Sierra, slates and phyllites 

 occur about Mineral King, Tulare County, in a belt some two miles 

 wide and fourteen long. Kaweah Peaks, the highest summits west 

 of the main crest in Tulare County, include the largest group of meta- 

 morphic sediments in the southern section of the range.'' 



Sandstones and quartzites are often found interbedded with the 

 shales and slates but sometimes form isolated patches ; the summit 

 of Mt. Dana is a sandstone though the bulk of the mountain is slate 

 and altered lava.' Quartzitic rocks occur in the Tahoe region near 

 Suz}^ Lake and on the headwaters of Rubicon River in Rockbound 

 Valley.® Quartz porphyry is exposed in the Mineral King region at 

 8500 feet elevation.^ 



Limestone is a rare rock in that part of the Sierra the plant 

 population of which is considered in this report, but is found in lenses 

 of varying size both in the northern and southern sections of the 

 range. 



The magmatic rocks of the Sierra Nevada include both intrusives 

 and extrusives, the former being vastly in excess both in area exposed 

 and in absolute amount. The intrusive rocks constitute the batho- 

 lithic core of the range and were probably once completely overlain 

 by the sedimentaries. The stratified rocks have now been reduced 

 by erosion to a relatively small amount, exposing the granitic rocks 

 which form far the larger part of the surface of the higher mountains, 

 the region inhabited by the boreal flora. 



The Sierran batholith contains several well defined rock species 

 of granitoid t^ype varying from normal granite to gabbro, its largest 

 constituent being a rock of intermediate character between granite 

 and diorite, known as granodiorite. This is the prevailing rock in a 

 broad belt from Genessee Valley, in Plumas County, southward to 

 the headwaters of Kings and Kern rivers. Granodiorite, as stated 

 by Lindgren," is distinguished mineralogically by having its soda- 

 lime feldspar at least equal to twice the alkali feldspar. Analyses^" 

 of samples from different parts of the range indicate that this preva- 

 lent rock species maintains a fairly constant character throughout 

 the Sierra. The analvses show the relation to granite and diorite, 



