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i* 



80 Ex. Doc. No. 41. 



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the atmosphere- not before existing. In the States there is scarcely 

 a night where the moisture \Yill not collect on the glasfe exposed to 

 the air, sufficient in two or three minutes to prevent the perfect 

 transmission o.f light. 



JVovcmhcr 9.— The effect of last night's dampness was felt in 

 the morning, for, although-the thermometer wa^only 37^3 the cold 

 was more sensible than in the dry regions at 25"^. 



We started in advance of the command to explore the. lower "belt 

 of mountains by w^hich we were encompassed. The first thing we 

 noticed in the gorge was a promontory of pitch-stone, against wincn 

 the river impinged with fearful force, for it was now descending at 

 arapid rate. Mounting to the top of the rock, on a beautiful table, 

 we found sunk six or eight perfectly symmetrical and w^ell-turned 

 holes, about ten inches deep and six or eight wide at top ; near 

 *one, in a remote place, was a pitch-stone well turned and fashioned 

 like a pestle. These could be nothing else than the^ corn-mills of 

 long extinct races. Above this bed of pitch-stone, a butte of cal- 

 careous sand-stone shot up to a great height, in the seams of which 

 were imbedded beautiful . crystals of quartz. Turning the sha^P' 

 angle of the promontory, ^ve discovered a high perpendicular cliff 

 of calcareous spar and baked argillaceoivs rock, against which the 

 river also abutted, seamed so as to represent distinctly the flames of 

 a volcano. A sketch was made of it, and is presented with these 

 notes. On the side of the river opposite the igneous rocks, the 

 butte 'rose in perpendicular and confused masse^^i 



This chain continued, not parallel, as I supposed, to the first de- 

 scribed barrier, but circled round to the east, and united with it. 

 It also united on tlie north side, forming a basin three or four miles 

 in diameter, in which we encamped last night. Except a few turn 

 of larrea Mtxicana, these hills were bare of vegetation. Away ou 

 to the south, and bordering on the banks of the river, covering the 

 surface of the ground for one or two feet, w^as an incrustration ol 

 black cellular lava or basalt, like that seen about the Raton. 

 Nothing more was wanted to* give the idea of an immense extinc 

 volcano. Through the centre of the crater the Gila now pursues 



its rapid course. 



The Gila at this point, released from its. mountain barrier, noy 

 off quietly at the rate df three miles an hour into a wide pl^j^?? 

 which extends soufh almost as far as the eye can reach. Upon this 

 plain mezquite, chamiza, the -green acacia, prosopis, ,artemis^^> 

 obione canescenr, and petahaya, were tlie only vegetation. In ^^ 

 spot only we found a_few bunches of grass; more than four-fii*^ 

 of the plain were destitute of vegetation; the. soil, a light bro*^ 

 loose sandy earth, I supposed contained something deleterious 

 vegetation 



•A specimen of this soil -was sutmltted to Professor Fraser, who says; " It is »1^ 



tro^Hj loose sandy earth containing- scarcely anything sokibl© in water^ the solution g"^^ 

 only faint indications of common salt and carbonat© of lime. A very small portion <» ^^ 

 pyrites is also contalnecl in it, but limagino its ^ant of fertility may more properly be ft^^ 

 uted to its deficiency in organic matters/' . 



