NATURAL AREAS AND REGIONS 



373 



gan. The Kankakee plain is a complex 

 of outwashed plains, much of it formerly 

 was marsh land. The interlobate mor- 

 aine extending from the northeast part 

 of the southwest for 100 mi. is a lake 

 region of Indiana. 



2. Climate 



The average temperature in the state 

 for January is 28, southern part is 33 

 and the northern part is 25. The lowest 

 state record is -33. 



The July average is 75 for the state, 

 for the southern part is 79 and for the 

 northern part is 73. The average maxi- 

 mum for June, July and August is 80. 

 The highest recorded temperature for 

 the state is 111. The average diurnal 

 fluctuation is 15 in winter and 20 in 

 the summer. The average rainfall for 

 the state is about 40 in. In the north 

 half one-tenth of this is snow and in the 

 south half one-twentieth is snow. The 

 rainfall in the north is less than 30 in. 

 and in the south more than 40 in. In 

 one small area it reaches 50 in. The 

 average annual evaporation from ex- 

 posed water surface is about 50 in. The 

 state receives an annual average of about 

 2800 hours of sunshine. The daily aver- 

 age for December is 3 hours and for 

 July slightly more than 10 hours. The 

 average growing season is 170 days. The 

 station with the shortest growing season 

 has 150 days and the extreme southwest 

 part of the state has nearly 200 days. 

 (See Visher, 1922. U. S. Weather Bu- 

 reau summaries of Climatological data 

 Nos. 67 and 68.) 



3. The original biota 



About seven-eighths of Indiana 

 formed a part of the hardwood belt. 

 The other eighth was prairie (Oak Grove 

 Savanna). This occupied the northern 

 part of the west side of the state and 

 was continuous with the prairie region 

 of Illinois (q.v.). The hardwood belt 

 has been described under Ohio (q.v.). 



4. Local biota 



A. Sand area biota. (Lacustrine area 

 south of Lake Michigan.) West of 



Gary this is a series of low ridges alter- 

 nating with long narrow shallow ponds 

 both of which parallel Lake Michigan. 

 "The ridges showed a series of biota: 

 cottonwood, jack pine (of which there 

 were several hundred acres immediately 

 west of Gary), black oak, white oak and 

 red oak. East of the city of Gary dunes 

 began and skirted the Lake into Michi- 

 gan. The dunes area is characterized 

 by cacti and lizards. (See Shelford, 

 Cowles, 1899, 1901.) 



B. The Kankakee Marshes. (The 

 Kankakee lacustrine.) The marshes of 

 this area were among the most extensive 

 in the middle west. It was drained by 

 the Kankakee river which was a stream 

 with great meanders and many broad 

 shallow stretches. The most notable 

 of these was called English lake, origin- 

 ally the largest water body in the state. 

 It formed a great breeding place for 

 aquatic birds and has a rather rich 

 mammalian fauna. (See Butler, 1897; 

 Hahn, 1908.) 



C. Caves. The cave region extends 

 from Crawford County on the Ohio River 

 north about 125 mi. (See section on 

 topography.) Wyandotte, Marengo, 

 Shawnee, and Mayfields are the best 

 known. A few hundred feet from the 

 entrance of a cave is a habitat of abso- 

 lute darkness, constant temperature 

 (52), and high humidity, and dependent 

 upon the inwash from the surface for all 

 basic organic food materials. 



The characteristic animals of the cave 

 are totally or partially blind and usually 

 without pigment. The blind fish (Am- 

 blyopsis spelaeus De Kay), the blind 

 crayfish (Cambarus pellucidus Packard), 

 the beetle (Anophthalmia tenius Horn) 

 and the cave isopod (Caecidotea stygia 

 Packard) are the most typical; in the 

 twilight regions occurs the cave sala- 

 mander (Eurijcea lacifuga); bats in 

 large numbers spend the winter in the 

 caves. Eight species have been taken 

 from Indiana caves (Hahn, 1908). 

 The plankton forms are all epigean spe- 

 cies. Almost any of the epigean fauna 

 of the cave region may be taken in the 

 caves except possibly the birds and some 



