248 Notes on Upper California. 



October 1. — The morning was, as usual, cool. At dawn the 

 thermometer was down to 32° F., while at noon of the preceding 

 day it had stood at 90° F. in the shade. We ascended the Clam- 

 mat two miles, and forded the stream in 2 J to 3 feet water. It 

 was 80 to 100 yards wide, and much of the way ran in rapids. 

 Passing to the northward of the rounded summit just alluded to, 

 over a region of sandstone hills, affording a dry soil and scanty 

 vegetation, we next traversed for five hours an undulating prairie, 

 much of which was as dry as the hills, and, besides, black and 

 desolate from the recent fires. The prairie in some parts abound- 

 ed in pebbles of milky quartz, indicating by their characters the 

 existence of talcose rocks in the vicinity. A generous rivulet 

 six to eight yards wide was finally reached, and afterwards a still 

 larger stream, with green banks, afforded a good place for encamp- 

 ment. The two unite and flow northwestward into the Clammat. 



After travelling upon this prairie for about six miles, we came 

 to a low outcropping ledge of sandstone, extending across the 

 plain from east to west, and dipping fifteen degrees to the north- 

 ward. Nearly six miles beyond, we passed a heap of volcanic 

 rocks, consisting of masses of grayish and reddish porphyritic 

 lava, one to ten cubic feet in size, lying together in a disorderly 

 pile. The rock contained crystals of glassy feldspar thickly dis- 

 seminated. As we continued on, these heaps of lava blocks be- 

 came numerous ; and the plain was thickly covered with rounded 

 and conical hillocks of broken lava, twenty to two hundred 

 feet high — averaging sixty feet. A few had table summits. Al- 

 though generally covered with soil, the black rocks outcropped 

 at top, and lay scattered over the surface. This soil was a red or 

 brownish-red earth, arising from decomposition, and it appeared 

 remarkable that it was scarcely at all mingled with the alluvium 

 of the plain : on the contrary, the soil of the prairie had the color 

 and characters due to a sandstone origin, proving that this Hil- 

 lock prairie had been leveled under water after the volcanic rocks 

 were thrown up. In the course of about five miles, these hillocks 

 of lava became so crowded together that the plain almost disap- 

 peared between their coalescing declivities ; and we observed be- 

 yond, that still nearer the mountains, the country gradually 

 changed to a region of rough rounded hills, which, increasing in 

 extent, rose into high ridges lying at the northern base of the 

 Shasty Peak. 



A hundred yards from our encampment, a spot in the plain 

 was covered with incrustations of salt, and salt plants (a species 

 of Salsola) were abundant. 



October 2. — Continuing southward, we had to the west, within 

 half a mile, high smooth-featured hills, evidently consisting of 

 sandstone; and about the same distance to the eastward, the 

 region of volcanic hillocks already described. In several places 





