134- Expedition to the 



ble, be introduced. This may easily be effected by burning 

 the prairies, at a proper season of the year, and sowing the 

 seeds of any of the more hardy cultivated graminae. Some of 

 the perennial plants common in the prairies, will, undoubted- 

 ly, be found difficult to exterminate; their strong roots pene- 

 trating to a great depth, and enveloping the rudiments of 

 new shoots placed beyond the reach of a fire on the surface. 

 The soil of the more fertile plains is penetrated with such 

 numbers of these as to present more resistance to the plough 

 than the oldest cultivated pastures. 



We had continued our march until near sunset, expecting 

 constantly to come in view of"the river, which we were per- 

 suaded must soon make a great bend to the south; but per- 

 ceiving the night would overtake us in the plains, we began 

 to search for a place to encamp. The bison paths in this 

 country are as frequent, and almost as conspicuous, as the 

 roads in the most populous parts of the United States. They 

 converge from all directions to the places where water is to 

 be found, and by following their guidance we were soon led 

 to a spot where was a small spring, dripping from the side 

 of a cliff of sandstone. The water collected in a little basin 

 at the foot of the cliff, and flowing a few rods down a nar- 

 row ravine disappeared in the sand. Having establishefl our 

 camp, we travelled down this ravine, searching for plants, 

 while any daylight remained. The rocks were beautifully 

 exposed, but exhibited no appearance unlike what we had 

 been accustomed to see along the river; the red indistinctly 

 stratified sand-rock, spotted and veined with plaister stone 

 and selenite. About the shelvings and crevices of the rocks 

 the slender corrolla of the CEnothera macrocarpa and the 

 purple blossoms of the Pentstemon bradburii lay withering 

 together, while the fading leaves and the ripening fruit re- 

 minded us that the summer was drawing to a close. 



On the morning following we resumed our march, alter- 

 ing our course from S. E. to N. E. The want of water in 



