558 



REPORT OF STATE GEOLOGIST. 



The smaller ones are the basins of former lakes, which have been filled 

 with sediment and vegetation. The largest are in the Kankakee basin, 

 and are the remaining vestiges of a glacial lake. Everywhere over the 

 central plain the divides are too flat and the slopes too gentle for good 

 drainage, and marshes abound. These, however, have been largely 

 drained by ditches. 



The above physiographic features are selected from the very com- 

 plete presentation of the subject by Dr. Dryer in his General Geog- 

 raphy of Indiana, as being those bearing most directly upon the dis- 

 tribution of the flora of the State. Those parts presented have at 

 times been abridged, the omitted parts, being as a rule, illustrations of 

 the special feature discussed. 



CLIMATE. 



Taking the record for 1896, which was very nearly a normal year, 

 the following summarizes the results drawn from observations upon 

 rainfall and temperature. 



"The mean temperature for January varied from 25° in the north 

 to 33° in the south, for July from 72° to 77°. The absolute extremes 

 of temperature for the State and year were 103° and — 22°. 



"The number of days in the year with average temperature below 

 freezing was ninety in the north and twenty in the south. The changes 

 of temperature are frequent, except in summer, when a period of two 

 or three months of uniformly warm, clear weather often occurs. 



"The mean rainfall is quite variable from year to year, ranges from 

 thirty-five inches in the north to forty-five inches in the south, and is 

 well distributed throughout the year, with a slight excess in spring. 

 The prevailing winds are from the southwest and the average wind 

 velocity, seven to nine miles per hour." 



The following tables taken from an article by Prof. H. A. Huston 

 in Indiana Agricultural Reports, Vol. 40, p. 503, 1898, will perhaps 

 serve to give a clearer idea of the climatal conditions of the State: 



AVERAGE TEMPERATURE FOR FOURTEEN YEARS- 



DEGREES FAHRENHEIT. 



AVERAGE. 



a 



•-3 



<X> 



u 



a 



§ 



< 



1 



a 





3 

 < 



-J 



a 



CO 



O 



Nov. 

 Dec. 



Northern 



23.4 



26.8 



35.1 



53.3 



60.2 



70.7 74.0 



70.9 



64.8 



51.0 



38.6 



30.9 



Central 



26.4 



30.2 



37.9 



52.3 



61.7 



72.0 



74.8 



71.6 



66.1 52.3 



40.4 



33.1 



Southern 



30.2 



33.9 



41.4 



55.8 



63.8 



73.6 



75.8 



74.4 



67.8 



54.7 



43.5 35.8 













