1800 REPORT OF THE CHIEF OF ENGINEERS. 



slope being too nearly a vertical, and without any bank by the water, a passsage was 

 constructed in a part of the river-bed for a distance as great as several hundred yards 

 in the shape of a pier. These viaducts were of superior workmanship, the height varied 

 from 8 to 10 feet, and with the side slope from the bottom commensurate with the 

 strength and endurance required, the top surface was at the widest points at least 10 

 feet across. (See Fig. II.) Mr. Wightman stated the cost of construction of the via- 

 ducts of the average dimension, 10 feet at base, 8 feet on a vertical, and 8 feet wide at 

 top, to be $1.50 per linear foot. At some points this was exceeded, the river with a 

 rapid current and a depth of 6 feet, occupying the place where the road now passes. 

 Here the blasting was also very expensive from the flint-like nature of the quartzite, 

 the working being so difficult that 30 steel drills per foot were used. The most ex- 

 pensive filling of this nature presented the following items of interest : 

 Length of fill, 441 feet. 

 Width at bottom, 14 to 16 feet. 

 Width at top, 10 feet. 

 Deepest water, 6 feet 2 inches. 

 Greatest depth of fill, 11 feet 9 inches. 

 Average depth of fill, 5 feet 10 inches. 

 Cost per linear foot, $1.72. 



Cost of blasting in quartzite, open work, $7.92 per cubic yard. 



The route of the road from Silverton is upon the right bank, crossing at the end of 



Baker's Fork, below the mouth of Mineral Creek, 

 to the east or left bank, by a plain but strongly 

 built bridge (Fig. Ill) 200 feet long, 18 feet wide, 

 and averaging about 14 feet above the water, pro- 

 vided with side rails, the flooring of hewn timber, 

 the upper surface squared and pinned by stringers. 

 The eastern end is higher than the other, the road 

 here being along solid rock. It continues down 

 this bank about 4-J miles, when it recrossd to the 

 other, at which point in September last were found 

 standing three piers of the old bridge, built the 

 year before and washed away during the high 

 water of the spring. Nearly all the timber was on 

 hand for rebuilding it, which was to be done during 

 October. The river here was 250 feet wide ; and 

 upon the right bank the road continues through- 

 out the entire canon, and on to the park below. 

 The mouth of Cascade Creek was a formidable obstacle. Inclosed near its mouth 

 in vertical walls, increasing to nearly 200 feet, a passage there was impossible. At 

 this point the nature of the canon of the Animas abruptly changes. From the end of 

 Baker's Park, for 17 miles without the windings of the river, it is encompassed by im- 

 posing mountains of quartzite towering one upon another. Instead of hugging the 

 trachytic formations, beginning at Sultan Mountain, and not far distant in its course, 

 the river boldly entered upon the more difficult task of forcing a passage between 

 these harder obstructions. 



From the upper brink of the grand canon the river like a silver thread may at inter- 

 vals be seen 4,000 to 5,000 feet below. The general course has thus far been south and 

 southwest ; with the accession of Cascade Creek, the departure from the great quartz- 

 ite region, the canon of the river changes to one more nearly straight, due south in 

 direction, its walls vertical, in places almost 1,000 feet in depth, where the river is 

 wholly inaccessible. This is situated in a valley of rolling hills, shut in on the east by 

 a ridge gradually diminishing to the south, while a range of cliffs of sandstone, encom- 

 passing the " Cliff Lakes" and continuing also to the south, from the western limit of 

 this depression and the boundary on the west of the park itself. 



The general average of the river's fall from Baker's to Animas Park is about 100 

 feet per mile. Near the beginning of the great "Box" Canon of the river there is de- 

 scent above the average, and falls and rapids of the river interpose too great for the 

 agility of the trout. While this fish of a superior size and flavor may be taken in the 

 Park below, none can be found in the Grand Canon nor in Baker's Park above. 



Leaning over the top of the bank at the edge of the canon, with a firm hold on a 

 rock or an overhanging tree and gazing down upon the water white with the foam of 

 its dashing and surging under and against the great black rocks that obstruct and 

 confine it, there is a feeling of awe that overcomes the behoider. 



When encamped near the Box Canon of the Animas, some hours were occupied in 

 attempts to reach the water's edge at several points, which were unsuccessful, owing 

 to the obstruction of vertical walls. In order to avoid these obstructions, the route of 

 the road was changed from the bottom of the Grand Canon, about 19 miles distant 

 from Silverton. A high hill was ascended by three steep gradients in a zigzag, the 

 mountain slope encircled, high retaining walls being essential, therefore, and Cascade 



