Notes on Upper California. 255 



often contorted, the cleavage was generally vertical, or nearly so. 

 But at this ridge we came upon a coarse sandstone and fine sili- 

 ceous conglomerate, extremely hard and compact. It had a light 

 color, and the rounded pebbles were mostly white, though at 

 times black. Beyond, we found again porphyritic basalt. The 

 hills for the last two hours of the day were more bare than usual, 

 being covered usually with shrubbery and but few trees. We 

 encamped on the upper prairie of the river, a fine grassy fiat 

 shaded by a few pines. 



October 7. — The sickness of two of our number detained us at 

 our encampment through the day. The rocks along the stream 

 were a blue argillite and compact sandstone, which dipped to the 

 northeast (compass course) about 60°. Some of it was a grayish 

 green rock breaking into regular fragments, and slightly glistening 

 with minute scales of mica. No fossils were observed. Across 

 the stream, the sandstone and argillite formed a precipice of 70 

 feet ; it was horizontally stratified, and very much fissured in va- 

 rious directions. The sandstone is an extremely hard compact 

 rock, in which it is difficult to distinguish minute quartzose 

 grains even with a lens. 



The boulders along the stream consisted mostly of the hypers- 

 thene rock, of grayish, greenish and brownish colors, and pearly 

 with hypersthene, along with masses of syenite and hornblende 

 rock, some of hornblendic gneiss and granite, and others of pud- 

 dingstone and basalt. 



October 8. — Soon after leaving our encampment on our way 

 down the stream, we found the sandstone passing into a conglom- 

 erate. We travelled over an undulating and hilly country, avoid- 

 ing a mountain of 2000 feet which we left between us and the 

 river, forded the stream three times in the course of the day, and 

 finally encamped again near its banks, on a fine meadow, under a 

 shade of oaks. The whole distance with small exceptions was 

 very rocky. Along the bottom of the valley, the rocks stood up 

 in ledges, ragged points and rude hillocks ; and during freshets 

 the river must present a scene of frightful grandeur. These rocks 

 consisted of puddingstone alternating with slate and sandstone, 

 a nd dipping from 30 to 00°, yet often vertical. At our second 

 ford, the strata were inclined 65° to the northwest and west- 

 northwest, (compass course,) and near by became vertical; they 

 consisted of both shale and puddingstone. The latter was a very 

 hard rock, made up of rounded siliceous pebbles, many like flint 

 and various in their colors. The rock might make good millstones. 

 The slates were fine grained, and neatly fissile, splitting into thin 

 plates. Quartz veins and seams were numerous. 



October 9. — Continued down the valley, over hills and ridges, 

 Mostly an arid country with little grass and only scattered pines 

 a nd oaks. The stream was enclosed between bare rocks on 



