HENDERSON] GEOLOGY AND TOPOGRAPHY 31 



by the ancient inhabitants for ceremonial purposes. It varies con- 

 siderably in ''ringing" qualities. The other basalts were used largely 

 in the manufacture of metates and other artifacts. That there are 

 older basalts in the vicinity is shown by the occurrence here, in the 

 sandstones and conglomerates, of angular fragments of basalt up 

 to at least six inches in diameter. The older basalt was not recognized 

 in situ. At the lower falls is an exposure of the brown and yellowish- 

 brown sandstone and conglomerate about 75 feet thick, with the 

 angular basalt pebbles scattered throughout, but larger and more 

 numerous in the upper 25 feet. No definite evidence of the age of 

 the sedimentaries at this point is available, but they are surely older 

 than the tufa and the basalt in contact with them, and antedate the 

 cutting of the canyon, yet they are not thoroughly consolidated. 

 They probably are of Santa Fe age. At the contact with the basalt 

 in two or three places the sandstone is ' ' burned " to a bright red, fading 

 in a few feet to yellow, then passing to the normal brow'nish color of 

 the formation. At one place the tufa also is burned by underlying 

 basalt, showing that the latter is intrusive, for if the basalt were older 

 than the tufa, then the latter would have been deposited on the cooled, 

 instead of on the intensely hot, surface of the basalt. Doctor Hewett 

 reports the same phenomena at Black Mesa, north of San Ildefonso, 

 and it is rumored that it occurs also near Buckman. 



A description of the canyon of El Rito de los Frijoles in some of 

 its principal features will answer for the neighboring canyons which 

 cut the plateau and drain into the Rio Grande. A better under- 

 standing may be derived from the accompanying photographic illus- 

 trations. The canyon has been cut into the tufa by the stream, 

 which through most of its course has not yet reached the base of the 

 formation. Therefore the walls are composed wholly of tufa except 

 for a mile or so above the mouth of the canyon, where, as indicated 

 in the preceding paragraph, the stream has cut down into the basalt 

 and sandstones. The important part of the canyon is 450 to 600 

 feet deep. The upper stretch consists of a deep, narrow gorge at the 

 bottom of the canyon, scarcely 25 feet wide in places and 50 to 75 

 feet deep, widening out thence to the top by a terrace or series of 

 terraces and slopes on each side, to a Avidth of some hundreds of feet. 

 This is all in the harder, up})er tufa and beyond the limits of the 

 portion of the canyon formerly occu])ied. Tributary gulches are 

 also narrow and precipitous. Even here it is usually, though not 

 always, much easier to ascend the southern wall than the northern one. 

 Downstream, where the creek has cut deeply into the more yielding 

 lower portion of the tufa, the bottom of the canyon widens into a valley 

 several hundred feet wide at the bottom and 1,700 feet in width at 

 the top, embracing a number of acres of tillable land, part of which 



