NATURAL AREAS AND REGIONS 



469 



number of smaller tracts set aside within 

 this area. This region is underlain by 

 igneous rocks and has long been noted 

 for its wonderful display of minerals of 

 which 52 varieties have been reported. 

 It is a relic of an ancient basin of thermal 

 springs. The forest is largely of hard- 

 woods in a region of coniferous forests. 

 It has attracted attention of the early 

 botanists, some of whom reported 

 botanical evidences indicating that the 

 cove was once marshy. Forty-seven 

 native trees have been listed from the 

 region. (See Ark. Geol. Survey Report, 

 Vol. 2, 1890.) 



Magnet, reached from Butterfield 4 mi. 

 northwest, or Cove Creek 2 mi. north on 

 Rock Island Ry. 



SELECTED BIBLIOGRAPHY ON ARKANSAS 

 FAUNA AND FLORA 



Buchholz, John T. Notes of Arkansas 

 Pteridophyta. Amer. Fern Jour., 14: 

 33-38. April-June, 1924. 



Buchholz, John T., and Wilbur R. Mat- 

 toon. Common forest trees of Arkan- 

 sas. Bull. Agr. Ext. Div. Univ. of 

 Ark., No. 180. November, 1924. Lit- 

 tle Rock. 



Harvey, F. L. Arboreal flora of Arkan- 

 sas. Amer. Jour. Forestry, 1883: 3-20. 



Same author in Bot. Gazette, 7: 12; 

 8: 355; 9: 195, 196; 10: 279-280; 5: 15; 

 39, 84; 91-93; 139^0; 6: 189-190; 

 213-15; 230, 273. 



Howell, A. H. Birds of Arkansas. 

 Bulletin No. 38; Biological Survey. 

 U. S. D. S. 1911. 



Harper, R. M. Phytogeographical notes 

 on the Coastal Plain of Arkansas. 

 Plant World, 17: 36-48. 1914. 



Harper, R. M. Same Undescribed Prai- 

 ries of Northeastern Arkansas. Plant 

 World, 20: 58-66. 1917. 



Palmer, E. J. The forest flora of the 

 Ozark region. Jour. Arnold Arbore- 

 tum, 2: 216, 232. 1921. 



Palmer, E. J. The Red River Forest at 

 Fulton, Arkansas. Jour. Arnold Ar- 

 boretum, 4: 8-33. 1923. 



Palmer, E. J. The ligneous flora of 

 Rich Mountain. Arkansas and Okla- 

 homa. Jour. Arnold Arboretum, 5: 

 108-134. April, 1924. 



Palmer, E. J., Two interesting ferns 

 from Arkansas. Amer. Fern Jour., 

 14: 39^1. April- June, 1924. 



Wheeler, H. E. Birds 9f Arkansas. 

 (A preliminary report with bibliogra- 

 phy by Howell.) Published by State 

 Bureau of Mines, Manuf. and Agr. 

 Little Rock, 1924. 



D. States Chiefly Oak Grove Savanna 



This type of vegetation which is 

 described on page 67 extends from 

 Minnesota to Texas just west of the 

 forest proper. Only those states which 

 are more largely of this than of any 

 other type are included here. Most 

 of Illinois and Iowa, and a large pro- 

 portion of Missouri and Oklahoma, are 

 covered by oak grove savanna. 



1. ILLINOIS 



BY THEODORE H. FRISON AND R. B. 

 MILLER 



I. GENERAL CONDITIONS 

 /. Topography 



Illinois is one of the states which form 

 the great Central Plain region of North 

 America. Though essentially a gently 

 rolling or flat plain, the general uniform- 

 ity of the surface is varied and broken 

 in most parts of the state. Chief 

 among the topographical features re- 

 sponsible for this unevenness are the 



extensive terminal moraines, the large 

 river systems and their accompanying 

 valleys, the unglaciated areas, and a 

 spur of the conspicously elevated Ozark 

 Highland. 



The north-south extent of the state 

 is approximately 5 latitude or 385 mi., 

 and the east-west extent of the state is 

 approximately 4 longitude or 216 mi. 

 The difference in elevation between the 

 highest and lowest points in the state 

 is less than a thousand feet, the highest 

 point being 1241 ft. above sea level in 

 Jo Daviess County and the lowest point 

 268 ft. above sea level at the lower 

 water mark where the Ohio and Missis- 

 sippi Rivers merge. 



2. Climate 



The climate of Illinois is determined 

 by its location in the interior of the 

 North American continent, the general 

 uniformity of elevation throughout the 

 state, its middle position in respect to 



