GEOLOGY OP CENTRAL WASHINGTON TERRITORY. 477 



masses had fallen from the inferior layers of what remained, showing that the work of destruc 

 tion was still going on. The bed of the water-course was about twenty-five feet beneath the 

 surface, and the vaults were from twenty-five to thirty feet wide, and fifteen or twenty in height. 

 The under side of the strata occasionally exhibited fluxures, resembling waves of progression. 

 Small stalactites of infiltration hung from the roof and walls, and stalagmites had been deposited 

 on the floor. This remarkable passage was traced at intervals for three or four miles, and 

 probably terminates in a branch of the Klikatat river crossed by the party the next day. 

 The Indian guide obtained snow from some cavity in this field, and reported that there was 

 one hole into which, if a stone was dropped, a long time elapsed before it was heard to strike. 



The soil of the valley which we descended consisted of a yellowish, light sandy loam, for the 

 most part thin, and lying directly upon the basalt. Lower down the mountain it became deeper, 

 and on the banks of the streams showed a depth of six or eight feet. Below the limit of the firs 

 the forest was open, and the ground covered with an abundant growth of excellent grass, forming 

 a good stock-range during the summer season. It is believed that wheat would flourish here ; 

 but the general want of water, except on the streams, and the coldness of the climate, will probably 

 prevent its occupation except for grazing. With this branch of the Klikatat river a further change 

 occurs in the rock, the range of hills lying to the east of it consisting of the same gray trap 

 noticed in the ascent from the Cathlapoot l, and, it would seem, bounding the efflux from the 

 mountains in this direction. From the cursory observations of this journey, it is inferred that the 

 more recent lava from these sources is confined within a particular basin, separated by well- 

 defined boundaries from the basalt of the prairies, from which it differs considerably in apparent 

 structure, and probably in composition also. Should a thorough geological exploration of this 

 region be hereafter undertaken, it will prove a matter of interest to trace up the course of the 

 streams, and fix the true relations of the existing volcanic peaks to these formations. 



Between the branches of the Klikatat is the Tahk prairie, the waters of which communicate 

 with the main river. It is about six miles in length, by a mile in its greatest width, and is 

 1,268 feet above Vancouver. A shallow, marshy lake occupies its lower end, the remains of 

 one which formerly covered the whole and extended much beyond the present bounds of the 

 open land. It is a favorite kamas and wappatoo ground of the Indians. The soil is a bluish clay, 

 baking very hard and cracking in the sun, and forms a great contrast with that bordering it, which 

 is light and pulverulent, and deeply colored by oxide of iron. The dark hornblende rock first 

 noticed on the Yakohtl occurred in place again here, but much more impregnated with iron. 

 The hills are barren and covered with scattered blocks. The main Klikatat river we found 

 running in a bed about two hundred feet below the general surface. It was at this season 

 (August 1 3) thirty or forty yards wide, and up to the flanks of the horses, with a pretty swift cur 

 rent. Its advantages for lumbering deserve particular attention. The yellow pine is found in 

 abundance, of excellent quality and suitable size, everywhere upon its banks, and logs can be 

 run at any season of the year without much difficulty to the Columbia. This river heads in 

 Mount Adams. The boulders in its bed resemble in every respect those found in the Cathlapoot l. 

 Its intersection with the trail is the lowest point touched by the main party from the time of 

 leaving the Cathlapoot l to that of reaching the Columbia below the Pisquouse. The descent 

 of the Cascade range may be considered as terminating here, and the survey of its eastern slope 

 to have commenced. 



The Sahpenis, the first branch of the Yakima encountered upon the route, appears also to head 

 in Mount Adams. It is divided from the Klikatat by a range of hills rising to the height of 3,600 

 feet, and its bed, though in a very deep canon, is much more elevated than that of the Klikatat. 

 The walls of this ravine are basaltic precipices rising in steps. The country here first begins to 

 open, exhibiting bald prairies seen at a great height upon the hills, and between it and the Simkwe 

 the forest disappears altogether. The fact was noticed by Lieut. Wilkes, in his memoir on West 

 ern America, that south of 48th parallel the line of forest terminates at about the same distance 



