mjttok.J CROSSING THE DESERT. 107 



landscape. The smaller cones are now seen to be very numerous, and 

 all of them are apparently perfect in form, as if time had wrought no 

 great ravage among them. The lapilli and pepcrino with which they 

 are covered, has become dull red by the oxidation of the iron, and (his 

 peculiar color is easily recognized though the cones are still far away. 

 Just before reaching the basaltic mesa we must make our choice between 

 two routes to the Toroweap, one direct, the other very circuitous. No 

 spring is to be found until we reach the further side of Mount Trumbull, 

 but we know of a large water-pocket on this side, which has never been 

 known to dry up. The spring water is sure to be good, but the water 

 in the pocket will depend for its quality upon the length of time which 

 has passed since the last heavy rain. Let us here choose the short cl- 

 one, and go to the water-pocket. 



Ascending the mesa which rises abruptly about 200 feet above the 

 Wonsits Plain, we find ourselves at once upon the basalt. The ground 

 is paved with cinders and fragments half buried in soil, the debris of 

 decaying lava sheets. These sheets are rarely of any great thickness, 

 seldom exceeding 30 or 40 feet, and often much less, and none of the 

 individual eruptions of lava seem to have covered any very great 

 expanse. Probably the area covered by the largest would be less than 

 a square mile. They show no perceptible differences in composition or 

 texture, and all are basalts of the most typical variety— very black and 

 ferruginous in the unweathered specimens and speckled with abundant 

 olivine. At the time of eruption they appear to have been in a state of 

 perfect liquidity, spreading out very thin and flowing rapidly and with 

 • ease. In none of them has erosion wrought much havoc, though here 

 and there some local destruction has been effected, most conspicuously 

 upon the edges of the principal mesa where the sheets have been under- 

 mined and their fragments scattered upon the plain below. The cones. 

 which stand thick around us, are still in good preservation. They are 

 of ordinary composition— mere piles of cinders thrown out of central 

 vents and dropping around it. The fume and froth of the lava surfaces, 

 the spongy inflated blocks, the lapilli and peperino, are not greatly 

 changed, though all of them here show the oxidation of the iron. We 

 wonder what their age may be; what time has elapsed since they vom- 

 ited lire and steam. But there is no clew — no natural record by which 

 such events can be calendared. Historically they have doubtless stood 

 in perfect repose for very many centuries. Not a trace of activity of any 

 kind is visible, and they are as perfectly quiescent as the dead volcanoes 

 oftheAuvergne or of Scotland. Geologically, they are extremely recent; 

 yet even here where historic antiquity merges into geologic recency the 

 one gives us no measure of the other. 



Following a course which winds among the silent cones and over 

 rough, flat surfaces of lava beds half buried in drifting sands, we at 

 length reach the border of a slight depression, into which we descend. 

 It is hardly noteworthy as a valley just here, and might be confounded 



