10 GULF TERTIARY OF TEXAS. 



a century ago. The present growth of timber on the plateau country is not 

 so large as that which originally covered it, but it is very dense, and in many 

 places is a great hinderance to travel. Numerous explanations have been given 

 for this increase of timber, but the one which is popularly accepted, and for 

 which there is most proof, is as follows: The Indians were accustomed every 

 autumn to burn the tall grass, which at that time became very dry and com- 

 bustible. This had the effect of killing off any small shoots and saplings 

 which had grown up during the previous year, and though it did not injure 

 the large timber it kept it from increasing in quantity. The object of the 

 Indians in doing this was doubtless to drive the game into certain parts of 

 the country; or else, knowing the tendency of the timber to grow up into a 

 dense forest, the object was to keep it down and thus facilitate his hunt. 

 Professor N. S. Shaler,* speaking of this matter, says: 



" These annual lorest fires were kindled either to drive the game towards the hunters or 

 to aid the growth of the fresh grass which springs up after the conflagration. In this way 

 the prairies were extended eastward to Indiana, and south to the Ohio River. At a point 

 west of Louisville, Kentucky, the prairie crossed that stream and extended south to the Cum- 

 berland River, near where Nashville now lies. In this latter region we have a clear example 

 of the process by which the country was deforested. When the whites first came to the Ohio 

 Valley this prairie region between the Ohio and the Cumberland rivers occupied the whole 

 belt of limestone land of Western Kentucky. Skirting the southern border of the western 

 coal field, it extended westward across the Cumberland and Tennessee rivers into the low 

 table-land which lies between the last named stream and the Mississippi River. About five 

 thousand square miles of this area were actually deforested, except where, beside the scanty 

 streams, the ground was too moist to permit the ravages of the annual conflagrations. On 

 the border of this area the old trees were not destroyed, but remained in the form of a very 

 open forest. The younger growth was, however, wanting. The reason for this is plain: 

 The older trees have a very thick outer bark, which served to protect them from the dam- 

 age which would be inflicted by the momentary heat of the burning leaves, while the tender 

 stems of the saplings were easily destroyed. Thus it came about that when the old trees 

 died they left no successors, and so the prairie steadily widened its area. 



" As soon as the Indians ceased to use Kentucky as an annual hunting ground the forests 

 rapidly regained their possession of all the prairie lands of this district. The annual burn- 

 ing of the surface ceased in the latter part of the last century ; in the second decade of this, 

 the whole of this great area was covered by a thin wood of young trees, which quickly 

 closed into a dense forest. At the present time all the parts of this field which have not 

 been deforested by man are thickly wooded. Some indications of a similar process of forest 

 restoration may be found in Indiana and Illinois ; but in those regions the annual rainfall is 

 less, and summer droughts, which are calculated to prevent the establishment of the young 

 trees, are more frequent and more prolonged than in Kentucky." 



The same phenomenon occurs in Arkansas, and the local explanation is the 

 same as that given above. Of course local causes may have entered into the 

 problem. The breaking of the sod by the plough and by rooting of hogs, 



*N. S. Shaler, " Aspects of the Earth," p. 287, New York, 1889. 



