170 CHARLES S. PR OS SEE 



Dakota sandstone) on the Platte River as resting on the Carbon- 

 iferous.' On this map the Permian was represented as thinning" 

 out and disappearing at a locality apparently several miles north 

 of Dunbar and northwest of Nebraska City ; while in the report 

 of 1872 Dr. Hayden clearly expressed this conclusion in describ- 

 ing the geology of Douglas and Sarpy counties. Dr. Hayden 

 said: "If the Permo-Carboniferous and the Permian were ever 

 deposited over this area, they were swept away by erosion prior 

 to the deposition of the Cretaceous rocks. If we follow the 

 valley of the Platte westward on the northern side, we shall see 

 the junction of the two great periods, Carboniferous and Creta- 

 ceous, and we shall find that the beds of the Dakota group, or 

 what we suppose to be the Lower Cretaceous beds of the west, 

 rest directly down on the limestones of the Upper Coal Meas- 

 ures."^ There seems to have been some error in coloring the 

 geological map accompanying this report, for on it the Permian 

 is represented as reaching the Platte valley at Saline, now called 

 Ashland, thirteen miles above Louisville, and then extending up 

 the Platte some twenty miles to Fremont. As a matter of fact 

 along the river to the east of Ashland are fine exposures of the 

 Dakota sandstone. 



Meek described a section of rocks on the north side of the 

 Platte River between three and four miles above its mouth (about 

 ten miles northeast of Louisville) which by their fossils are 

 shown to belong to the Upper Carboniferous, probably the 

 Wabaunsee formation. ^ 



On the ridge to the south of Louisville are exposures of the 

 lower part of the Dakota formation. One of these is in the 

 "Fire Clay" quarry of Captain Hoover, one and one-half miles 

 south of the village (Sec. 27, Tp. 12, Range ii) where an open- 

 ing of about fifty feet has been made in working the middle part 

 of the section for fire clay. The exposure begins on the bank 

 of a small run with an approximate altitude of iioo feet A. T. 



'Proc. Acad. Nat. Sci., Phil., Vol. X. 

 ^ Fin. Rep. Geol. Sur. Neb., p. 7. 

 T' Ibid., pp. .^0-93. 



