8 



Utica Slate and 



becoming interstratified with beds of shale. In 01m§tead county, 

 still further north, the Trenton also contains numerous beds of shale; 

 and the Galena is still further reduced. The beds are traceable by- 

 continuous or frequent out-crops throughout Goodhue and Rice 

 counties, with an increasing amount of contained shale in the Trenton, 

 and finally with the complete loss of the Galena." 



The Galena formation, attaining its maximum development in the 

 area bordering on northern Illinois, south-western Wisconsin and 

 eastern Iowa diminishes in volume to the north, north-east and north- 

 west. In the area mentioned it has a thickness of from 200 to 2*75 

 feet; it is not to be found near the primary rocks on the old shore 

 line of the northern border of the basin, havina; thinned out in that 

 direction. To the south it passes beneath the superior formations, 

 with the exception of an area in Missouri, where, although having 

 considerable volume, it is less than in its central area. In south- 

 western Illinois the Thebes sandstone rests directly upon the Trenton 

 limestone, occupying the same position as the Galena limestone does 

 in Illinois and Missouri. 



Having reviewed the Utica epoch in its stratigraphical character and 

 geographical distribution, over its eastern, northern and western ex- 

 tension of the Appalachian basin, there remains the great central 

 area over which, from its being remote from the eastern and northern 

 shore lines, the sediments were deposited with less abrupt changes 

 in their character and with less disturbance of the then living fauna. 



In 1842 Prof. James Hall said of the lower beds exposed near 

 Cincinnati : 



" At Newport, Kentucky, opposite to Cincinnati and at one or 

 two other places in the vicinity, there is a green shale with the 

 Triarthrus, graptolites and a few encrinal joints, showing the same 

 assemblage of fossils and in the same position as the Utica slate of 

 New York." 



The rock below these beds he considered the equivalent of the 

 Trenton limestone and above the equivalent of the sandstones of 

 Salmon river and the shales and sandstones of Pulaski.' Thirty- 

 seven years of study and investigation of this formation has not 

 changed the value or correctness of this statement, as is well shown 

 by the recent action of the committee on Geological Nomenclature, 

 of the Cincinnati Society of Natural History. '-^ 



^ ]!^otes on the Geology of the Western States. Amer. Journ. Sci. Arts, p. 61. 

 1843. 



" The fossils found in the, strata, for twenty feet or more above low water mark 

 of the Ohio river, in the first ward of the city of Cincinnati, and on Crawfish 

 creek, in the eastern part of the city, and in Tayfor's creek east of Newport, 

 Kentucky, at an elevation of more than fifty feet above low water mark in the 



