HARVKE.] GEOLOGY NORTHEEN LIGNITIC AREA. 175 



Spending depression, of course, exists in the lower side of the section 

 above. This upper columned, jointed, splintered mass of lava shows 

 no signs of bedding, but it rests below in a mass of volcanic conglom- 

 erate, containing patches of white- weathered tuff, in all a few hundred 

 feet in thickness, dipping somewhat to the northwest, and forming a 

 zone of most curious pinnacled forms surrounding the base of the 

 steep upper slopes of the peak. At the very base a small patch of 

 lava was observed, consisting of a hard white matrix, with numerous 

 imbedded grains of sanadine and quartz, apparently a typical western 

 rhyolite. The conglomerate and basalt i^robably rest directly upon it. 



The summit of White-Face Mountain and its western spurs seemed 

 covered with the same lavas as covered Corral Peak. 



In the upper part of the East Fork of Troublesome Creek several dips 

 of the lignitic sandstones were observed at right angles to the stream, 

 or southeastward, some of perhaps 10°, thus forming a gentle mono- 

 clinal of the valley. Low^er down, dips of 5° or 8° to the southwest take 

 their place, and the inclination of the strata being greater than that of 

 the stream, they gradually disappear beneath it. The valley is not as 

 deeply cut as that of the Willow, the first more abrupt rise being less, 

 and the semi-terraced slopes rising rather gently on either hand, inter- 

 sected by innumerable small ravines. A little lov/er, about five miles 

 above the junction with the West Fork, the river turns westward and 

 approaches a ridge into a narrowing gorge through which it enters, the 

 high hills on either side becoming capped with volcanic material. As 

 the stream cuts through the gently westward-dipping lignitic beds, the 

 capping lava descends more and more, until the palisaded canon is 

 wholly in it, the lignitic disappearing beneath it, the stream finally 

 emerging from between the gradually lowering sides to its junction with 

 the West Fork, in the flat, low-terraced basin of the Lower Troublesome 

 tributary to that of the Grand. This volcanic material lies upon the 

 hill-slope with a western dip of 6"^ to 1°, and consists of poorly strati- 

 fied or irregular volcanic conglomerates, some white tuffs, but mostly of 

 dark or black basaltic lavas, some columnar, which form the i)alisades. 

 On the south side of the caiion a well-defined bed shows at one point a 

 thickness estimated at seven or eight hundred feet. Some of the lavas 

 observed were very fine-drained, with conchoidal fracture, some with 

 rough resinous surfaces, with the usual variations of appearance com- 

 mon in basalts. Except the peculiar tabular structure, some were un- 

 distinguishable from those of Corral Peak, and it is quite possible that 

 these lavas flowed down from that source. Inclining westward, the lava 

 ends abruptly at the canon's mouth in a steep slope of about 100 feet, 

 which descends to a narrow lake-bed terrace skirting its base, which in 

 turn descends in a slope of 40 feet to the river " bottom" of the West 

 Fork. (The section is shown in Plate III, section 4, east end.) Down 

 the Troublesome, the lava seems to end abruptly along the river in a 

 similar manner for some distance, being bordered on the west by the 

 terraced lake-beds of the stream, and thus concealing the western edge 

 of the great lignitic area from view. From here to the Hot Springs the 

 southern limit of this formation was not traced. It is probably some- 

 what concealed by this same lava flow, but it seems quite likely that 

 near Corral Creek, and on to Mount Bross, the lignitic beds may rest on 

 the granite, or on the upturned edges of the Cretaceous, as it certainly 

 does just beyond, near the Hot Springs. Somewhere near this line, and 

 not far below the junction of the two forks, are some sulphur springs 

 said to be similar to those near Mount Bross, but cold. As it is not un- 

 likely that the former may have an outlet similar to the latter, their 



