surface was covered with a dense growth of semi-tropical 

 plants and forest timber. The general surface of the land was 

 low, level and swampy, and upon slight depression was easily 

 overspread by the seas, engulfing and covering its growth of 

 vegetation with sediment, forming our coal beds. This altern- 

 ating sea and land surface continued for millions of years, or, 

 until the close of the carboniferous or coal-making age, when 

 the Appalachian range of mountains began to make their 

 appearance by the folding and crumpling of the earth's surface 

 along the eastern border of the great interior sea. The eleva- 

 tion of this mountain range out of the sea, with the consequent 

 moderate elevation of adjoining regions to the west, perma- 

 nently raised the surface of Indiana above the level of the 

 ocean, at the end of the Palaeozoic era. From that time until 

 the glacial period, a time computed by Geologists to have been 

 many millions of years, a time at least sufficiently long for 

 four miles in thickness of the Appalachian range of mountains 

 to be removed by subaerial decay and erosion. During this 

 long period, the surface of Indiana was subject to sunshine and 

 shadow, rains, snows and frost, forests covered the uplands, and 

 swamps were present in the lowlands, streams intersected its 

 surface, and all was perhaps little unlike that which has 

 occurred since the history of man. During these immense 

 ages, the surface of the rocks raised up out of the seas decayed 

 by subaerial disintegration and chemical solution, to great 

 depths, and was eroded and channeled by the streams until 

 the surface of Indiana presented an extremely broken and deso- 

 late appearance, with numerous gullys, canons and water- 

 falls, and all streams flowing over rock bottoms, much as we 

 find the present condition of the lower third of the state, but 

 in a more exaggerated form, from the fact that the glacial 

 drift from the upper two-thirds of the state has served by over- 

 flow washings to modify much of its rugged and uneven char- 

 acter. The great trough of the Ohio river is one of the remains 

 of this period, it being from one to four miles in breadth and 

 from four to five hundred feet deep. Also the lower part of 

 the Wabash river, with many other small Indiana tributaries of 



