60 GUIDEBOOK OF THE WESTERN UNITED STATES. 



These rocks contain fossil plants and shells of fresh-water mollusks, 

 although brackish-water and marine fossils occur near their base. 



Between Dana and Walcott the strata are bent up in one of the 

 great arches or anticlines of this much-disturbed region, Edsoii is 



on the Lewis shale, but the beds of the North Park 

 formation (Tertiarj^) extend to the railroad from tlie 



02n^ia^664 miies^^ ' soutli- .A mile farther southwest, beyond a short 



tunnel, is a deep cut through the crest of tlie St, ^fary 

 anticline, which consists of the arched sandstone of the Mesaverde 

 formation. The crest of the ridge is formed of this sandstone, which 

 is harder and has therefore resisted erosion better than the shaly 

 beds that originally covered it. i 



South of the tumiel the train again crosses the Lew^s shale and the 

 ^^ Lower Laramie '^ formation before it reaches Walcott. The town 



of Walcott is built on the North Park formation, 



^ ^^ * which here covers the older strata. This formation 



Elevation G,618 feet. ^^^^^ j^g ^^^^ f^^^^ ^ ^^ p ]^ q^ j^ -^ 



Oni-^na fJ\^ mime - j j -^^ ^ ^ 



occupies an extensive area and contains thick beds 

 of coal. From Walcott a branch road runs south to Saratoga and 

 Encampment. Saratoga is on Platte River and is well laiowoi to 



Omaha 669 miles. 



sportsmen for its hunting and fishing. Here are some hot sulphur 

 springs and a well that furnishes a mineral water sold under a dis- 

 tinctive name. Encampment, 43 miles south of Walcott, at the end 

 of the branch line, is the center of a copper-mining district which for- 

 merly produced considerable ore but is not now very active. This 

 district is in the Sierra Madre. Copper was discovered here in 1 868, 

 but not until 1881 did the district become productive. Altogether it 

 has yielded over 20,000,000 pounds of copper. Gold, silver, and 

 other metals have been found in small quantities. The mines are 

 in crystalline and metamorphic rods, of pre-Cambrian age, cut by 

 intrusive rocks, including gabbro, which is supposed to be the source 

 of the copper ore. 



About 2 miles due north of Walcott is a prominent hill known as 

 St. Mary Peak, which rises 7,496 feet above sea level. This peak and 

 the ridge extending northwestward from it are composed of upfolded 

 beds of the Mesaverde formation. The strata, during the process of 

 folding, were broken and thrust upon one another in such a way that 

 those east of the fracture were pushed up over those west of it, so 

 that certain beds of the Mesaverde formation now rest upon younger 

 beds that were originally laid down on top of that formation. 



Two miles west of Walcott the railroad leaves the nearly liorizontal 

 beds of the North Park formation and reaches the steeply inclined 

 massive yellow sandstones of the Mesaverde formation, which are 

 carved by erosion into a great variety of forms. These sandstones 

 make a conspicuous ridge that extends northwest ^^^rd for many 



