APPENDIX SS. 1755 



The western ends of the Uncompahgre Mountains are washed hy waters belonging 

 to the San Miguel ; their northern slopes are drained hy the river of the same name, and 

 in part hy streams flowing, like the Uncompahgre itself, into the Gunnison. The lat- 

 ter, rising far to the north, has a general westerly course, flows into the Grand, and, 

 watering a magnificent country, has for its tributaries streams that drain some of the 

 finest mineral and agricultural land in the State, a large part of which, however, is 

 the territory of the savage. 



THE SAN LUIS VALLEY. 



The great San Luis Valley, properly so called, though often alluded to as a park, 

 is bounded on the east by the Sangre de Cristo Range of the Rocky Mountain sys- 

 tem, on the west by the San Jnan and other mountains, constituting the great conti- 

 nental divide. Although partially in Xew Mexico, it lies chiefly in Colorado, extending 

 from the point where the Rio Grande crosses the line of New Mexico, nearly 100 

 miles in direction west of north, with a varying width, being at different places 40 

 miles across in an air line. 



In its northern part it is drained by the San Luis Creek, rising in the extreme north 

 near the Pundio Pass, receiving the Saguache Creek from the west. 



The Sangre de Cristo Range, rising to over 13,000 feet, has for its prominent passes 

 the Pundio in the north, the Mosca in the east, and the Sangre de Cristo and Abeyta, 

 further south, the latter two continuous depressions in the range, all four being util- 

 ized as passage-ways for wagon-roads. A point near the Abeyta has enabled the 

 Denver and Rio Grande Railroad (narrow gauge) to surmount the range and enter 

 the San Lnis Valley. Upon the western side the slopes of the range are far more 

 abrupt than upon the eastern. This causes more rapid flow of the streams entering 

 the valley, and in its upper part a large number disappear in the sandy soil, reach- 

 ing the deepest depression of the valley underground. The San Luis lakes are with- 

 out an outlet, and owing to the almost level surface of the water-flow, a series of 

 swamps arise, advancing and retreating in area with the rise and fall of the streams, 

 the surfaces being the haunts of myriads of water fowl. 



Upon the western side of the valley, emerging from the mountains as if from a gate- 

 way, at Del Xorte appears the Rio Grande coursing southeast and then to the south, 

 gathering in the Alamosa, La Jara, and Conejos on the Avest, the Trinchera, the 

 Culebra. and Costilla upon the east; all streams that enter the valley upon either side 

 above these arc totally lost. 



About 6 miles below the Culebra's mouth, not far below the Chavez ferry, where 

 the plain is 25 feet above the water, its surface heightens to the south, and the canon 

 of the Rio Grande begins. Deepening as it proceeds, till it is nearly 1,000 feet below 

 the surface, with basaltic sides almost of bare cliffs, it presents a vast gorge, bespeak- 

 ing the ruin of the past, through which the river has forced its passage. 



The steep mountain sides, bounding the valley ; the glistening dunes piled about 

 the Mosca Pass; the depression in its central part receiving all but not yielding any 

 waters that flow to it, the little hillrocks of sand lower down, with long stretches 

 encountered, from which the whirling winds toss up sandy pillars that may be often 

 noticed to an immense height flying here and there: the rise in the plain to the south 

 and the canon beyond of undoubted aqueous erosion, all suggest the vast inland sea of 

 the great geological past, when the land above possessed a vegetation at present un- 

 known ; and on Avater and shore were probably mammalia compared to which ours are 

 scarcely more than pigmies. 



MOUNTAIN RANGES AND DETACHED SPURS. 



The large number of outlying masses, separate sierras, and detached spurs from the 

 main range, all part and parcel of the Rocky Mountain system, within the San Juan 

 proper, may be best understood by assuming the vertex of the great < of the con- 

 tinental divide as the center of a square whose side is 30 miles, within which will be 

 found more than 240 lofty peaks rising in every direction from 10,000 to 14,000 feet in 

 height, silent monuments of the gigantic upheavals of nature. So complicated is the 

 topography of this region that a thorough orographic description, defining and de- 

 lineating in detail the various geological axes of the distinct sierras or detached 

 groups, with their separate radial axes referred to geometrical figures, would, unless 

 of great length, be so complicated and perplexing as to result in little save confusion 

 worse confounded. We will therefore attempt but a general summary of the largest 

 masses with reference to the great divide, and the rivers already mentioned. 



The section within this square has been aptly likened to one of the '-domes of the 

 continent." It certainly is so of the Rocky Mountain system within the United 

 States. Nowhere can be found, for such an area, so great a precipitation. Loftier 

 peaks than rise in the continental divide are found without it, particularly north of 

 the vertex; the rivers rise here and flow to every point of the compass, as a casual 

 glance at the map will demonstrate. The Rio Grande to the east, draining the in- 



