TO JUNCTION OF GRAND AND GREEN RIVERS. 103 



The area occupied by the most recent strata found in the San Juan country is but 

 limited. The detached buttes which they form, and to which reference has before been 

 made, stretch southwesterly from the north end of Nacimiento Mountain toward San 

 Mateo, along the line of the divide between the Chaco and the Chelly; in other words, 

 between the waters of the Rio Granda and those of the San Juan. Westward from this 

 summit the table-land, which I have described in the preceding chapters as the pla- 

 teau of the Upper San Juan, extends to the distance of one hundred miles or more, 

 terminating in the mural faces of the Mesa Verde. Through this plateau Cafion 

 Largo and its continuation, the valley of the San Juan, are cut to the meridian of the 

 Sierra de la Plata; thence, westward, the lower plateau of the Sage-plain stretches to 

 the margin of the valley of the Colorado. In this lower plateau the trough of the San 

 Juan is also deeply sunk; cutting through the Lower Cretaceous group, and exposing, 

 especially toward its mouth, many hundred feet of the underlying Triassic formation. 

 Throughout the whole of its course through the table-lands the valley of the San Juan 

 is a narrow trough, bounded by abrupt, often perpendicular, rocky sides; its rich and 

 verdant bottom-lands forming a thread of fertility which traverses a region elsewhere 

 arid and barren. 



On our way south from the Sierra Abajo we struck the San Juan at a point some 

 fifty miles or more above its mouth. Before descending from the plateau of the Sage- 

 plain into the valley of the river, we obtained from several points views which swept 

 over all the country bordering the lower part of its course. Of these that from the 

 vicinity of Camp 33 was peculiarly comprehensive and grand; revealing features so 

 novel and striking that I regarded them as worthy of somewhat detailed description in 

 my note-book,, That description is as follows : 



" Soon after leaving camp (33) we obtained a beautiful view of all the country bor- 

 dering the Lower San Juan, of which nearly 10,000 square miles were at once visible. 

 From this point the eye swept a great semicircle from the Sierra de la Plata in the east 

 around southward to the Bear's Ears in the west. From the Sierra de la Plata the long 

 line of the lofty Mesa Verde stretched southward to the valley of the San Juan, there 

 terminating in high and abrupt cliffs. In the open valley of the river stood the isolated 

 pinnacles of the Needles, a peculiar and picturesque feature even at this great distance. 

 In the southeast the bold front of the northern end of the Sierra del Carrizo rose frown- 

 ingly from the immediate borders of the valley, and stretched away southward in a 

 succession of peaks till lost in the distance. 



"Directly south the view was bounded by the high and distant mesas of the Na- 

 va jo country, succeeded in the southwest by the still more lofty battlements of the great 

 white mesa formerly seen by us from the Moqui Villages, and described in my report to 

 Lieutenant Ives. Of these high table-lands the outlines were not only distinctly visible, 

 but grand and impressive at the distance of a hundred miles. Nearly west from us a, 

 great gap opened in the liigh table-lands which limit the view in that direction ; tl uit 

 through which the San Juan flows to its junction with the Colorado. The features 

 presented by this remarkable gate-way are among the most striking and impressive 

 of any included in the scenery of the Colorado country. The distance between the 

 mesa walls on the north and south is perhaps ten miles, and scattered over the interval 



