WILD GRASSES. 115 



Some old frontiersmen claim that the perpetuation of this grass 

 depends on its seeds being scattered by the buffaloes, and that 

 when they ceased to visit their old haunts it would necessarily have to 

 die out. But it is difficult to understand why the foraging of domestic 

 cattle would not have the same effect. It cannot be ascribed to the 

 buffaloes' manner of cropping this grass. These animals some- 

 times pastured this grass more closely and constantly than domestic 

 cattle. I have sometimes followed a herd of a few thousand buf- 

 falo and they seemed to eat the short, sparse grass in places almost 

 out of the ground, leaving almost bare soil behind them. Causes 

 with which neither the buffaloes nor domestic cattle have anything 

 to do, evidently produce its extermination. The rate of its disap- 

 pearance varies somewhat. In northern Nebraska it retreated west- 

 ward at the rate of about twenty miles a year, until it reached its 

 present eastern boundary. Along the Republican Valley, during 

 some years, it has retreated at the rate of thirty miles a year, and 

 other grasses, alreadv mentioned in this chapter, took its place. In 

 other years it has retreated more slowly. In favored localities it 

 lingers behind several years longer, but even the alkali spots finally 

 give it up. It is remarkable that the grasses that take its place are 

 such as are indigenous to comparatively moist regions. I suggest, 

 therefore, that change of climate, especially increase of rainfall, has 

 most to do with this phenomenon. In Chapter IV was shown the 

 constantly increasing rainfall in the Stitc. It is the only fact com- 

 petent to explain all the phenomena accompanying the disappear- 

 ance of this grass on which the millions of buffalo, elk, deer and 

 antelope had previously fed for ages. 



ORIGIN OF OUR FLORA. 



One of the questions that most frequently occurs to the thinking 

 mind is when and how did our Flora originate? Did it originate 

 here, or did it come by migration from some other region: 



The earliest memorials of our present Flora are found engraven 

 on the rocks of the lowest member of the cretaceous rocks of the 

 west, known as the Dakota group*. In the chapter on the cre- 

 taceous deposits, the geological features of these rocks are given. 

 Here are found impressions of the first oaks, cottonwoods, willows, 

 maples, gums, hickories, walnuts, plums, cedars, pines, grapes, etc. 

 The formation in which these early memorials are found, stretches 



*See Lisquereux, Report on Cretaceous Flora. 



