MORGAN] RUINS IN THE CANON OF THE RIO CHACO. 155 
Two separate explorations and reports upon the Chaco ruins have been 
made. The first was by Lieut. J. H. Simpson, who examined them in 1849 
and first brought them to notice, and the second was a re-examination by 
William H. Jackson in 1877. He was connected with Prof. F. V. Hayden’s 
Geological and Geographical Survey of the Territories, and his report is in 
that of Professor Hayden, published in 1878, p. 411. 
The canon of the Chaco, which commences about one hundred and ten 
miles northwest from Santo Domingo, on the Rio Grande, is quite remark- 
able. It has enough of the characteristics of the canon to justify the appli- 
cation of this peculiar term But it differs from the great canons in the 
lowness of the bordering walls and in the great breadth of the space between. 
Neither Simpson nor Jackson describe the canon or valley with as much 
particularity as could be desired, but Mr. Jackson has furnished a map, 
Fig. 29, showing the course of the stream with the walls of the canon 
shaded in, and with the breaks or gullies through these walls reduced to a 
scale. This shows that the level plain between the encompassing walls 
ranges from half a mile to a mile in places. The walls of the canon are 
composed of friable sandstone, and are usually vertical. Their height is 
not given with precision. The engraving also shows the outline forms and 
comparative size of the several structures, with specimens of three varieties 
of masonry used in the walls. No.2 shows an alternation of courses of 
stone from four to six inches thick and from eight to twelve inches long, with 
intervening courses of several thin stones. The same alternation of courses 
reappears in the pueblos in ruins on the Animas River, about sixty miles 
north. The canon commences very much like the McEImo Canon in South- 
western Colorado, whose vertical walls are at first about three feet high, 
with a level space between from three hundred’ to five hundred feet in 
width; its walls rising slowly as you descend. Without a present running 
stream, and bordered with open prairie land, it makes a novel appearance 
to the eye. Lieutenant Simpson remarks that after leaving the pueblo 
Pintado, which is above the commencement of the canon, “two miles over 
a slightly rolling country, our general course still being to the northwest, 
brought us to the commencement of the Canon de Chaco, its width here 
being about two hundred yards. Friable sandstone rocks, massive above, 
