A WALK IN THE YELLOWSTONE PARK. 79 



Still again, the newest strata lie along the Sea and CnJf 

 shores, and dip down under the water. These sheets of sedi- 

 ments are undisturbed. Beneath these are generally older 

 strata which have a corresponding dip. These seaward dip- 

 ping strata are Csenozoic and Mesozoic. When we descend to 

 the Palaeozoic strata we often find them considerably folded 

 and irregular. 



In general, the present positions of the strata may be ex- 

 plained as if they had been produced thus : First, the uni- 

 versal ocean deposited sediments which hardened into Eozoic 

 rocks which universally underlie. Then some portion of the 

 bottom was uplifted to daylight, and the sediments of the next, 

 or Palaeozoic, -5Con were not universal. Next the uplifted 

 regions were further uplifted, and some of the Palaeozoic sedi- 

 ments appeared along the margins of the Eozoic. Then fol- 

 lowed Mesozoic sedimentation, another uplift of the same 

 regions; then Csenozoic sedimentation and other uplifts. 

 Meanwhile the destructive work of erosion was in progress, and 

 the original shapes of the uplifted strata, already disguised by 

 many movements, were further obscured by the wearing down 

 of extensive formations, and the obliteration of some. But 

 of all this we shall catch more satisfactory glimpses hereafter. 



A WALK IN THE YE>Lix)^?vsTO]srE FARK. 



THERMAL WATERS'. 



IN the north-western corner of the territory of Wyoming 

 is a tract sixty-five miles long and fifty-five miles broad which 

 has been reserved by act of Congress (March 1, 1872) as a 

 national park or reservation "dedicated and set apart as a 

 public park or pleasuring ground for the benefit and enjoy- 

 ment of the people." This was done on the recommendation 

 of the national geologist, Dr. F. V. Hay den. The tract on 

 the north extends about two miles into the territory of Mon- 

 tana, and on the west, two and a half miles into Montana and 

 Idaho. For natural scenery it is one of the most remarkable 



