CHARACTER OF THE DISTRICT. 273 



The belt of Carboniferous limestone encircling the area of metamor- 

 phic rocks is only about four miles in width at the foothills near Spring 

 and Eapid Creeks, but to the north it becomes broader and extends a 

 greater distance back from the plains into the hills, its western edge follow- 

 ing along the north side of the valley of Box Elder as an irregularly broken 

 cliff or wall. Soon after entering the limestone both Box Elder and Elk 

 Creeks sink in their beds and disappear from five to eight miles from the 

 plains. The water must escape through subterranean channels, as, a short 

 distance below where it sinks among the bowlders, the bare limestone bed- 

 rock is exposed perfectly dry for some distance across the whole width of 

 the bottom of the canon. 



Contrasted with the Spring or Rapid Creek districts, the area of slates 

 is comparatively flat, and the grade or descent of the stream much less, 

 becoming greater in the limestone canon, where for long distances the 

 Box Elder flows in a swift current over bare bed-rock. Box Elder is not 

 a single or main powerful stream like most of the other creeks in the Hills, 

 but an aggregate of numerous small branches formed by insignificant 

 brooks, which do not unite until the stream enters the limestone. Many of 

 these head branches are mere threads of water, or contain water only in 

 occasional deep holes, and are dry during a greater portion of the year, 

 the largest fork being but 6 to 10 feet wide and veiy shallow. Small 

 ponds and broad marshy flats overgrown with a swamp of willows and low 

 bushes are often encountered on the forks of this stream. They are pro- 

 duced by the beaver in damming back the water in the level valleys, and 

 from the same cause large and deep beds of black peaty muck have been 

 formed by the gradual deposition of vegetable matter in these still pools. 



Elk Creek is a stream not quite as large as Box Elder, but resembling 

 it in other respects. For three miles of its course it flows through a narrow 

 and crooked canon in the slates, then emerges into an open and flat valley, 

 with broad grass flats skirting its banks, through which it winds for about 

 three miles, and, entering the great limestone formation, sinks in the bed of 

 the canon and disappears. Where the dry ravine of this stream opens 

 upon the red valley at the edge of the plains, several fine springs of excel- 

 lent cold water burst out from under the Triassic limestone, and form a 

 18 B H 



