234 RIVERBY 



What gives the great fertility to the blue-grass 

 region is the old limestone rock, laid down in the 

 ancient Silurian seas, which comes to the surface 

 over all this part of the State and makes the soil by 

 its disintegration. The earth's surface seems once to 

 have bulged up here like a great bubble, and then 

 have been planed or ground off by the elements. 

 This wearing away process removed all the more re- 

 cent formations, the coal beds and the conglomerate 

 or other rocks beneath them, and left this ancient 

 limestone exposed. Its continued decay keeps up 

 the fertility of the soil. Wheat and corn and clover 

 are rotated for fifty years upon the same fields with- 

 out manure, and without any falling off in their pro- 

 ductiveness. Where the soil is removed, the rock 

 presents that rough, honeycombed appearance which 

 surfaces do that have been worm-eaten instead of 

 worn. The tooth which has gnawed, and is still 

 gnawing it, is the carbonic acid carried into the earth 

 by rain-water. Hence, unlike the prairies of the 

 West, the fertility of this soil perpetually renews 

 itself. The blue-grass seems native to this region; 

 any field left to itself will presently be covered with 

 blue-grass. It is not cut for hay, but is for grazing 

 alone. Fields which have been protected during 

 the fall yield good pasturage even in winter. And a 

 Kentucky winter is no light affair, the mercury often 

 falling fifteen or twenty degrees below zero. 



I saw but one new bird in Kentucky, namely, the 

 lark finch, and but one pair of those. This is a 

 Western bird of the sparrow kind which is slowly 



