OCR Text |
Show TAIXST OF THX PANNACK. 91 stones, altered shales, and veins of the same feldspathic took nbtioed in the pass. The strata wete inclined east by north* a$ en angle of 70°. The ridge seems to run a. Httle west of north, until it disappears in the valley of the Snake River. Upon the sammit of this " divide" was found what was at first thought to be altered coal^ but upon farther examination it appeared to be an aluminous rock, containing but a small trace of . carbonate of lime. Its oolour was black, hardness greater than that/ of feldspar, and the form a rhombic prism. The limestone was crystalline, and contained numerous'specimens of shells and corals, but in sp altered a state that it was impossible to determine. them. The length of the fork of the Pannaok which we descended is sixteen miles. It pursues a westerly direction, until it joins the main stream, which latter flows from the southward, through what appeared to be a well- defined valley. The ground for a road is excellent, with, only one or two exceptions, which are not of a serious character. » On descending, the dividing ridge. in which it heads, the rocks were hidden by a black, rich soil; occasional boulders of granite were s& n on the surface, but no. section could be obtained until we came to a gorge about five miles down the valley. Here the river cuts through a much lower ridge of hills, composed of limestone, dipping to the east, at an angle of about # 8°: below this the stream has cut its bed through secondary hills . formed of argillaceous sandstpno and day, both of which are white, and mixed with pieces of obsidian and occasional boulders of serpentine: still lower'down the valley, a . section in a ravine to the right of'the road, discovered some rocks which- might almost be considered cretaceous-; alternating with white argiUaceons sandstone, they contained a considerable quantity of organic remains, principally coral, but so muoh altered by heat that it was impossible to determine them with precision* The dip of these strata was about 10° north- east. The beds were covered by the remains of disaggregated conglomerate* composed principally of porphyry and granite. Proceeding down the stream* metamorphio sandjatonesy crystallised almost to the whiteness of white quarts, were found, forming escarpments of the lower hills;. « short distance below this point, a ridge of trills, composed of limestone, shales, and red sandstone, extended across, the valley; they were all much inclined, with a dip to. the east. At this point, where the river cuts a padsagfc through this chain, a mass of feldspathic rock was Seem The dip |