132 GUIDEBOOK OF THE WESTERN UNITED STATES. 



and still preserves its nearly level surface. The lava sheet that caps 

 the high hill on the north side of the canyon below Wolcott was prob- 

 ably once a part of this same flow or flows but has been separated 

 from it by the canyon cut by Colorado River. 



After passing milepost 3-12 and a small cut a few hundred yards 



beyond the railroad track reaches the bank of Colorado River, which 



it follows to the western border of Colorado. This 



Dotsero. p^rt of the country is noted for its cattle and 



Elevation 6,167 feet, hoj^ggg ^nd the sidiug of Dotsero is maintained 



Denver 343 miles. ' _ _ ° 



largely for their shipment. There are no red rocks 

 in the valley of Colorado River just below th& mouth of Eagle 

 River, but the rocks there exposed are about as hard as the soft 

 red and green shale and sandstone above. At first the traveler 

 may not be able to identify any of the dull-gray and slate-colored 

 rocks below Eagle River with those he has seen farther upstream, 

 but a comparison of the section and of the order of the formations 

 may show him that these beds are the same as the heavy cliff-making 

 sandstone and shale which he saw just below Minturn. It might be 

 supposed that the same formation should show the same composition 

 and hardness wherever it is exposed, but as these formations con- 

 sisted originall}^ of sand, clay, and limy materials that were de- 

 posited in some body of standing water, either a lake or the sea, it 

 is apparent that the character of the formation at any place must 

 depend largely upon the kind of material there swept into the body 

 of water by the streams, and as the land near by was probably com- 

 posed of various kinds of rocks, which furnished various kinds of 

 material, it does not seem strange that at one locality a formation 

 may consist largely of sandstone and at another of shale. Changes 

 from sandstone or shale to limestone are more rare, but such changes 

 are observed in many parts of the country. The soft materials, in- 

 cluding some coal beds that are exposed below Eagle River, belong 

 to the Weber formation, which is in the lower part of the upper Car- 

 boniferous rocks. 



The rocks rise gently westward, and at milepost 345 the massive 

 layers of the Leadville limestone rise from river level. This point 

 marks the beginning of one of the most noted canyons on the line 

 of the Denver & Rio Grande Western Railroad, the canyon of Colo- 

 rado River that stretches in unbroken beauty and grandeur from 

 this point to Glenwood Springs, a distance of 15 miles. (See Pis. 

 LVII, 5, LVIII, and LIX.) This great canyon was trenched by the 

 river in an immense upfold of hard beds, which include all the sedi- 

 mentary rocks that the railroad has crossed in the canyons above, 

 and into the underlying granite, to a total depth of 800 to 1,000 feet. 

 The first appearance of the Leadville limestone, noted above, near 

 milepost 345, is marked by a warm sulphur spring, very similar to 



