4 THE PLAINS. 



from the Missouri Eiver to the Pacific Ocean, is a vast 

 plateau, more or less elevated, through the general level 

 of which many mountain ranges and systems push their 

 heads to the limit of perpetual snow. 



The term ' The Plains ' is, however, specially applied 

 to a comparatively restricted portion of this great area, 

 extending from the Guadalupe Mountains of Texas on 

 the south to the British line on the north from the 

 Missouri Eiver on the east to the Eocky Mountains on 

 the west from the thirtieth to the fiftieth parallel of 

 latitude, and from the ninety-fifth to the one hundred and 

 fifth degree of longitude. 



To the scientific geologist the plains is a most 

 interesting and exhaustive field. Its prominent geological 

 features have not been so confused and defaced as in the 

 other elevations, and the problems presented appear so 

 comparatively easy as to attract the interest and attention 

 of even the most unscientific observer. 



The first great upheaval that which lifted from the 

 waters the great mass of the Eocky Mountains must 

 have resulted in mountain heights to which those now on 

 earth are comparatively molehills. 



From the ruins of these mountains the foundation of 

 the plains was to be formed. Their bases ceaselessly 

 lashed by the ever restless ocean, their summits beaten 

 by the deluges of rain which must have marked that 

 early epoch, they were torn to fragments, and the detritus, 

 carried nearer or farther by the currents, were deposited 

 in the layers where they now appear in a new creation of 

 solid rocks. 



At their base, and stretching far to the eastward, are 

 now miles upon miles of rounded stones, pebbles, and 

 sand, the washings of ages, deposited at the mouths of 

 rivers and streams in form of bars, or piled in measure- 

 less heaps by the action of glaciers. 



Almost the whole eastern foot of the mountain is now 

 bounded by this formation. If forms the whole country 



