614 Part IV. - Chapter 4. 
as a barrier between the Cascade and Sierra Nevada Mountains has been 
described (see ante p. 256.). It remains to discuss the plant formations of the 
Shasta Area. 
ı. Coniferous Forest Formations. 
Mount Shasta rises from a forested region and the mountain itself is 
forest-covered up to an altitude of 7,500 to 8,000 feet. The trees of the lower 
slopes are those of the surrounding region, but those on the upper slopes are 
different '). 
Pinus ponderosa Belt. This formation is an open forest belt extending up 
to an altitude on the south and west sides to about 5,500 feet. Pinus ponderosa 
is the most characteristic tree of this formation and the lower slopes. The only 
gap in the continuity of this forest is a strip about 8 miles (12,8 km) in length 
on the cold northeast slopes, where Pinus Murrayana grows. On the south and 
west, the open pine forest of the basal slopes is interrupted by extensive parks 
of chaparral consisting of Arctostaphylos patula and Ceanothus velutinus. North- 
west of Shasta the forest of Pinus ponderosa is interrupted by the open plain 
of the Shasta Valley: on the south it is practically continuous to the base of 
Lassen Butte and thence along the flanks of the Sierra for 350 miles (472 km); on 
the southwest, according to Merriam, it follows the canyon of the Sacramento 
River to a little below Delta, where, in the bottom of the canyon and warmer 
slopes it mixes with Pinus sabiniana. On the cooler and higher canyon slopes 
and adjacent foot hills Pinus ponderosa continues to the border of the Sacra- 
mento Valley. West of Shasta this formation covers all but the highest ele- 
vations of the Scott Mountains and reach up a considerable distance over 
the east arm of the Salmon Mountains where Pinus ponderosa is mixed 
with Pseudotsuga Douglasii, Pinus Lambertiana and Libocedrus decurrens. Still 
farther west the forest of Pinus ponderosa occurs in greater or less extent in 
the valleys of Russian Creek, north and south forks of Salmon, Trinity and 
Klamath rivers and at appropriate altitudes on the west arm of Salmon and 
Trinity Mountains’). 
The forest of Pinus ponderosa is nowhere pure over any large area, but is sprinkled with 
Pinus Lambertiana, Libocedrus decurrens, Pseudotsuga Douglasii, Abies concolor var. Lowiana, 
Pinus attenuata (a narrow interrupted tongue of which pushes up Panther Creek) Quercus cali- 
fornica (= Q. Kelloggii), Acer macrophyllum, A. glabrum, A. circinatum, Alnus tenuifolia. he 
chaparral of this belt consists of Ceanothus cordulatus, C. integerrimus, C. (Cerastes) prostratus, 
C. velutinus, and Cercocarpus ledifolius. 
_— 
Abies shastensis Belt. This belt?) is not connected with similar forests 
elsewhere, because it occupies Mount Shasta above the forest of Pinus 
ponderosa. It forms a belt averaging two or three miles in breadth and 2,000 
I) MERRIAM, C. Hart: Results of a biological Survey of Mount Shasta California. North 
American Fauna, No. 16, 1899: 30. 
2) SHINN, CHARLES H.: Among the Siskiyou Forests. Garden and Forest II: 598, Dec. ıı, 1889. 
3) CoVILLE, C. V.: The Shasta Fir. Garden and Forest X: 516 
