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We have now traced the growth of the area comprising Indiana 

 through Paleozoic time. We have seen how that area gradually appeared 

 above old ocean's rim. But it was not yet the "Indiana of Nature"— the 

 finished product of the ages ready for the advent of man. Centuries un- 

 told had yet to come and go before it was complete— centuries during 

 which changes of momentous importance were to come to pass. For, as 

 yet, no palm, no angiosperm or floAvering plant with seeds, no osseous or 

 common fish, no reptile, no bird, no mammal had come to be upon the 

 surface of the earth. All these were evolved from pre-existing forms 

 during the age or era immediately succeeding the Carboniferous or final 

 period of Paleozoic time. This age is known as that of the Mesozoic or 

 Middle Time, represented by the Triassic, Jurassic and Cretaceous eras. 

 For our purpose there may be combined with these eras the Tertiary of 

 Cenozoic or recent time. During the myriads of years ascribed to these 

 eras, while vast changes were taking place in other parts of the American 

 Continent, the sux-face of Indiana probably remained above sea level. 

 On it there grew the plants and over it there doubtless roamed, in their 

 turn, the animals of each successive era, but as its surface was above the 

 sea, they left no fossil bone or footprint to tell us of their presence. 



All this time, however, the silent processes of nature were unceasing 

 in their labor, and wrought great changes in the surface of the future 

 State. Decay and erosion were in action then as they are today. Sun- 

 shine and rain, wind and frost, trickling rills and strong streams were 

 ever at work, softening and sculpturing and wearing down the exposed 

 rocks, forming clays and sand and gravel and bearing them away to lower 

 levels. At the close of the Tertiary Era, the entire surface of what is now 

 Indiana resembled that of today in the driftless area of its southern part, 

 being cut up by erosion into a complex network of valleys, ridges and 

 isolated hills. In certain portions of the northern half great streams, of 

 which there are now no surface indications, had worn their channels a 

 half mile in width, 200 feet or more down into the solid Niagara lime- 

 stone. The Ohio River valley, a trench from one to six miles wide and 

 400 feet deep, was mainly eroded during this period, as was also the 

 greater portion of the Wabash Valley, from Huntington to its mouth. 

 Everywhere over the surface was a thin soil, formed from decaying rocks 

 and vegetation, poorer, perhaps, than much of that which at present 

 covers the surface of the driftless area, where the xmderlying limestones 

 and shales have been the parent rock. In this soil grew the cedar and the 



