354 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 57 



The provisional classification of the pre-Ordovician formations 

 in the Upper Mississippi Valley is as follows : 



Canadian 



U 



B 

 u 



a, 



Formations. 



Shakopee 



60' 

 Oneota 



no' 

 Madison 



40' 

 Mendota 



Jordan (Winchell 1874) 

 60-80' 



St. Lawrence (Winchell 

 120' 1874) 



Franconia (Berkey i 

 85' 



Dresbach (Winchell i 

 100' 



Eau Claire (Ulrich MSS. 

 About 100' 1914) 



Mt. Simon (Ulrich MSS. 

 235'+ 1914) 



Lithologic characters. 



Dolomite. 

 Dolomite, 

 Magnesian and calcareous sandstone. 



Dolomite. 



Heavy bedded soft, rather coarse- 

 grained, yellowish sandstone. 



Soft fine-grained brown, red, green 

 or ash-colored sandstone often 

 dolomitic near top. 



Yellow and ash-colored argillaceo- 

 calcareous, thin-bedded rock near 

 middle, and green sands inter- 

 bedded with yellow sandstones in 

 lower third. 



A series of thin and thick-bedded 

 usually soft sandstones with much 

 green material throughout or only 

 in portions. The upper fifty feet 

 often harder than the underlying 

 beds and containing a considerable 

 fauna, especially species of Co- 

 nasf>is. In many localities other 

 fossiliferous beds occur in the 

 central and lower portions. 



Massive-bedded, rather coarse- 

 grained sandstone, with a thin bed 

 of shale at the base and shaly 

 sandstone near the middle. Fossils 

 at the top and base, consisting 

 almost entirely of shells of Dicel- 

 lomus and LingiileUa. 



Mostly thin-1 edded, in part shaly 

 sandstone, with many fossiliferous 

 layers, including Owen's Menom- 

 onie and Wooster's Eau Claire 

 trilobite zones. Usually a coarse 

 white friable sandstone with Dicel- 

 ! omits and Lingulella'at the base. 

 Numerous characteristic trilobites, 

 Crepicephalus iowensis being one 

 of the best of the guide fossils. 



A series of coarse sandstones and 

 grits resting on pre-Cambrian 

 granite. About 225 feet are shown 

 in the bluffs at Eau Claire and 50 

 feet of the base at Chippewa Falls, 

 Wisconsin. Except Scolithns bor- 

 ings no fossils have been found. 



