Birds of Indiana. 519 



ELEVATION. 



"According to Powell's division of the United States into physio- 

 graphic regions, Indiana lies mostly on the Ice Plains, but includes a 

 small portion of the Lake Plains on the north and of the Alleghany 

 Plateau on the southeast. The highest land in the State, in southern 

 Eandolph county, is 1,285 feet above tide; the lowest, at the south- 

 west corner is 313 feet. The area above 1,000 feet comprises 2,850 

 square miles, in three tracts: (1) An irregular area around the head- 

 waters of the Whitewater river, in Union, Waj^ne, Eandolph, Dela- 

 ware, Henry, Eush, Decatur, Franklin and Eipley counties;* (2) a 

 narrow crescentic ridge in Brown county; (3) a considerable area in 

 Steuben, DeKalb, Noble and Lagrange counties. Isolated peaks rise 

 in Brown county to 1,172 feet and in Steuben to 1,200 feet. The 

 area between 500 and 1,000 feet in elevation is 28,800 square miles 

 and that below 500 feet is 4,700 square miles. The average elevation 

 of the state is 700 feet. 



PHYSIOGRAPHIC REGIONS. 



"The most striking physical contrast in Indiana is that between the 

 glaciated and unglaciated areas. A comparison of the topographic 

 map with that showing the revised glacial boundary brings out this 

 contrast sharply. North of the limit of drift the contour lines run in 

 large curves and are far apart, showing the general smoothness and 

 monotony of the surface. South of the glacial boundary the lines are 

 crowded and extremely tortuous, showing a surface much cut up. 

 The limit of drift incloses and fits this area of l)roken surface as a 

 man's coat fits his shoulders. 



''The Ohio Slope. — That portion of the State which slopes directly 

 to the Ohio, including the driftless area and the southeastern part 

 of the drift plain, is a region of deep, narrow valleys, bounded by 

 precipitous bluffs and separated by sharp, irregular divides. Isolated 

 knobs and buttes are numerous; the crests and summits are from 300 

 to 500 feet above the valley bottoms. The streams are rapid and 

 broken by frequent cataracts. All open out into the Ohio Valley, a 

 trench from one to six miles wide, 400 feet deep and bounded by steep 

 bluffs. 



"The Central Plain. — North of an irregular line extending in a 

 general direction from Eichmond to Terre Haute, and south of the 

 westward flowing portion of the Wabash from Fort Wayne to Attica, 



* Also Fayette and a part of Dearborn. 



