300 



southeastward, where it merges into the hazeobscnred, flat-topped 

 buttes and conical peaks in the region east of the Canadian basin. The 

 latter is hidden from view by the high bounding Tertiary plateau, while 

 the great mesa as effectually shuts out the view of the more distant 

 plains. It is a region marked by long lines of parallel ridges, diversi- 

 fied by immense tableland and isolated volcanic cones, to which the 

 mirage lends its illusory repetition of phantom mountains, which one 

 moment are so real as almost to deceive, but the next to melt into 

 strange fantastic shapes, until one can scarce believe they have aught 

 to do with things terrestrial, but rather strange creations of the sky. 



From the camp on the Upper Yermejo, a little valley leads by a grad- 

 ual ascent to the summit of the Francisco Pass over the Eaton Hills. 

 In a distance of about four miles, the rise is about 900 feet, the summit 

 of the pass being 8,600 feet in elevation, and situated just within the 

 border* of Colorado. To the west, a rather high, rugged ridge, which 

 is apparently composed of metamorphic rocks, possibly the tilted Cre- 

 taceous, continues for some distance along the valley, when it is re- 

 placed by the low Tertiary ridges, which latter continue to bound the 

 eastern side of the valley to the summit, often rising 300 to 500 feet 

 above its bed, and in whose sides thin beds of lignite are known to 

 exist. 



Liooking back over the depression of the park country into which the 

 little valley opens, one of the finest views of Costilla Peak is gained, 

 which, from the north, presents a pyramidal outliue, the abrupt north- 

 ern face bastioned and rent by profound chasms reaching nearly to the 

 summit, which rises between one and two thousand feet above the forest- 

 line. Away to the southward, in a notch to the right of a prominent 

 cone marking an angle in the watershed, or main range, the dome of 

 Great Baldy just rises into view, mantled by a recent fall of snow. To 

 the northwest, and quite near at hand, the diverse and lofty summits of 

 the Yermejo Mountains tower above the nearer hills; and northward, 

 overlooking a succession of low ridges with indications of narrow val- 

 leys and park-like openings similar to those south of the pass, the 

 Spanish Peaks appear; the eastern peak peculiar on account of its 

 symmetrical, conical outline, the western and apparently highest mass 

 arching up into a jagged crest, which falls off in an abrupt descent to 

 the west. The lower hills flanking the broad basis from which the 

 Spanish Peaks spring, and which pertain to the Tertiary plateau in its 

 extension north of the Raton Hills, gently slope eastward toward the 

 plains, ])recisely in the same manner observed in the plateau south of 

 the Eatons. No considerable extent of the latter ridge is commanded 

 from this point, the nearer eminences hiding from view as well the 

 plateau extending southward. To the west, the Tertiary formation 

 apparently abuts upon the metamorphic ridges in the near vicinity, and 

 which it may partially conceal. There is, however, marked dissimilarity 

 in. the accompanying topographical features here observed as compared 

 with the great Colorado divide, with which the Eaten Hills possess a 

 marked resemblance in many other respects. Here there is no marked 

 valley of erosion intervening between the Tertiary and the granitic 

 mountain-wall, such as exists in the pass at the initial point of the Col- 

 orado divide; consequently, in the immediate vicinity of the Francisco 

 Pass, the connection between these later sedimentary deposits and the 

 older metamorphosed formations, as well as their relation to the granitic 

 and igneous nucleus of the main range, is not so clearly manifest. 

 Whether they extend over the Cretaceous hog-back, concealing its 

 tilted ledges from view, or whether this ridge is curved to the westward 



