80 GEOLOGY. 



These different ridges vary somewhat in geological structure, and, as we shall have occasion 

 to notice hereafter, serve to give an additional variety to the mountain scenery. However 

 viewed, nakedness is the prevailing character, the exceptions heing lew and far between. 



The summit ridge, attaining a variable height above the sea of 3,000 to 5,000 feet, presents 

 in its wintry covering of snow, and its richer verdancy of summer growth, some of the finer 

 features of California scenery. Without possessing a marked Alpine character, it approaches it 

 in a sparse growth of pines, and other coniferfe ; while the frequent fogs bathing its sides favor 

 the growth of lichens and mosses almost unknown in the lower regions, except in a few evan- 

 escent forms during the rainy season. 



The view to the west takes in the bold outline of treeless ranges stretching in a dim line 

 seaward. Looking towards the east, the less obstructed view traces the line of diminished 

 vegetation, plainly and somewhat abruptly marked, in going downward on the steep slope. 

 Irregular mountain peaks, and ranges of a dull, ashy color stand out in view in close proximity, 

 and below all stretches the brown plains of the desert, extending to the hazy marked line of the 

 Colorado river. 



Descending from the summit westward, you pass down luxuriantly grassed valleys, edged 

 with scattering pine and oak groves, and watered by cold, perennial streams, until an abrupt 

 descent to a lower level brings you again into wider basin-shai^ed valleys, bounded on all sides 

 by rocky ridges. The streams spread out into low grassy or sedgy marshes, and the i^ine growth 

 gives place to the lowland oak, with its peculiar undergrowth. Continuing thus by a series of 

 gentle swells and abrupt descents, you pass almost insensibly the different ranges, till the 

 smooth, brown outline of the coast range indicates your proximity to the sea. 



In the summer season you wind down broad valleys, marked by the dry, pebbly beds of winter 

 streams ; herbage is dry and wiry, and water confined to a few willow-shaded marshes or 

 isolated springs. Opening on the sea, you traverse dry moorland hills, dropping down to the 

 sea-level in the bed of some wide, sandy valley, which, with its sides bounded by precipitous 

 walls of coarse sand and pebbles, finally spreads out into wide saline flats, cut up by tide 

 estuaries, and terminates on the ocean beach. 



Proceeding from the same summit ridge in the opposite direction (eastward) from its pine 

 fringed heights and rich green sward, you drop by a steep descent into pent-up valleys bounded 

 by ashy-colored mountains. The streams whicli flow in the upland ravines are soon lost in 

 their thirsty beds. The valleys near their exit from the mountains slope in a regular plane, 

 covered by wide and dry beds of streams. Occasionally the passage of an irregular mountain 

 chain is marked by a rude defile, cutting through mica slate, or highly micaceous granite. 

 Thus winding with occasional j^assages over ridges of the same character, flanked with rough 

 pebbles, the desert opens before you, its table-land being generally gained by a steep ascent 

 from the deep bed of some dried up stream, along the course of which the geological tertiary 

 formation is strongly marked in thick layers of marl or sand, surmounted by a varying bed of 

 rounded pebbles. 



Over the desert waste, furrowed occasi.mally by the dry sandy beds of rain streams, you pass 

 insensibly down till the lake formation of "New Kiver" comes into view. Here the soil 

 acquires a sedimentary character ; fresh-water shells are scattered here and there. The imme- 

 diate lake edges and lower depressions are bordered by a growth of mezquite, while, in its 



