ee NEW TRACKS IN NORTH AMERICA. 
space whatever on either side between the bed of the stream 
and the rocks, so that the only passage is in the river itself. : 
The action of the water, moreover, has hollowed out the base 
of the southern wall-rock for from 20 to 30 feet of its 
thickness, so that we rode under the rock itself for some : 
distance. 4 
The first “narrows,” as we called this passage, having ~ 
been passed, we came to an open Space of some fifteen acres, — 
giving us a good camping ground and plenty of grass for the — 
stock. This space is situated about the centre of the cafion, — 
and is very beautiful, being filled with splendid timber, 
cotton-wood, sycamore, live oak, ash, willow, walnut, and q 
grotesque old mezquits of most unusual size. Fine branches { 
of mistletoe hung from many of the trees; we met no girls, 4 
however, on this occasion, but the: laughter-loving parasite 
was a great surprise. 3 
Just past this open space a great change takes place. In 
order, it would almost seem, that. the traveller should not — 
weary of the cold grey sandstone and conglomerate forma- 
tions, the sombre tints and horizontal Strata, large quantities . 
of volcanic rock, with their smooth facets and their rich tints q 
varying from purple and red to black, burst into view, and j 
alter completely the appearance of the walls. A deep rich — 
fringe of basaltic columns adorns the terraces on either side, and — 
this lavaform coating is bright and shining ; the edges are as q 
sharp in outline as if cut with a knife, and produce fantastic 
forms in the shape of turrets, &c., quite different in appear- 4 
ance from those met with previously. Nor is the change tobe — 
seen only in the rocks—the vegetation immediately shows : 
the difference of soil ; and, identical in position with the new y 
strata, appeared for the first time on our route the Cereus j 
Gganteus, the largest cactus with which botanists are | 
