133 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



The fact that we find no undisturbed beds of rocks of a more 

 recent age than the Devonian, does not prove that the face of the 

 country has been continuously above the water since that age. 

 We have reason to believe that much of northern Illinois and of 

 Iowa was beneath the ocean during much of the Carboniferous 

 age ; and if exjDOsed to surface degradation through the long dura- 

 tion of the ?tIesozoic ages, including the eroding forces of the Qua- 

 ternary times, we may judge what an amount of the original sur- 

 face rocks has been worn away I 



Sufficient attention has not been directed to high beds of gravel 

 that occur in many places. Such beds of gravel, if closely in- 

 spected, may, in many cases, reveal traces of what has been the 

 character of the rocks that have been disintegrated from the sur- 

 face of the country. 



The upper Mississippi is one of the oldest rivers of the globe ; 

 it once flowed at a much higher elevation than at present. The 

 bed of the river has once had an elevation fully as high as the tops 

 of the present bluffs ; for, while the river has for millions of years 

 been wearing its channel continually deeper, the tops of the bluffs 

 and the whole face of the country have also been wearing away by 

 aqueous action. We should expect to find some traces of river 

 gravel at high elevations. 



When we consider the vast thickness of the Mesozoic formations 

 that are revealed in the western mountain regions, and reflect on 

 the duration of time required for the accumulation of this material 

 in the bottoms of the oceans, we should also bear in mind that 

 the material of which all these Mesozoic rocks were formed was 

 mainly abraded from the face of the older continents, and was 

 transported by rivers and spread over tlie floors of the oceans. 

 From tht' thickness of the Mesozoic rocks, including the Permian, 

 Triassic. Jurassic, Cretaceous, Eocene, Miocene and Pliocene, we 

 may judge what a quantity of matei ial has been thus reiuoved. 



March otii, 1880. — Geological Section. 



Mr. W. H. Pratt in the cliair. Four members jiresent. 



Messrs. Gass and Blumer had just returned fi'om a trip to I^ouisa 

 county, and exhibited a second elephant pipe, a broken bird pipe, 

 and a small copper axe, found in a mound on the farm of Mr. Haas. 



Mr. Pratt presented some fossils collected at East Davenport. 



