22 ECONOMIC BOTANY OF ALABAMA. 



cover the uplands while many of the streams have cut 

 down into the hard rocks of the former, causing an ex- 

 tensive overlapping, or rather interlocking, of two more 

 or less distinct kinds of country. On a large map this 

 interlocking could be shown pretty accurately, but in the 

 present case the best that can be done is to strike an 

 average between the two regions as nearly as possible, 

 by means of a dotted line. 



In the southern tier of counties, especially eastward, 

 the geology has to be partly disregarded for a different 

 reason. There the strata are nearly level, and at the 

 same time variable and poor in fossils, and the geolo- 

 gists themselves are not yet fully agreed upon how they 

 should be mapped; but it is possible to define geograph- 

 ical divisions in that quarter pretty well on a basis of 

 soil, topography and vegetation, without knowing much 

 about the geology. 



The principal sources of information for the present 

 map, arranged chronologically, are as follows: 



1. Agricultural map of Alabama by Dr. Eugene A. Smith, 1883. 

 (Smith 6 and 7 in bibliography.) 



2. Large geological map of Alabama, with explanatory chart, 

 also by Dr. Smith, 1894. (A smaller edition of this map, first 

 issued in 1904, resembles the present geographical map in size 

 and to some extent in the absence of minute details.) 



3. Small geographical map by Dr. Smith in J. H. Phillips's Ala- 

 bama supplement to Frye's Complete Geography, 1897. 



4. Map of floral areas, frontispiece of Mohr's Plant Life of Ala- 

 bama, 1901. (Mohr 8 in bibliography.) 



5. Some of the government soil maps of Alabama counties. 

 (See U. S. Dept. Agriculture in bibliography.) 



6. Field work of the writer, 1905-6, 1908, 1910, 1911, 1912-13, 

 extending into every county. The principal innovations from this 

 source are in the southeastern quarter of the state. 



