NO. 1850. KNOBSTOXE CRIXOID FAUNA— SPRINGER. 177 



name for the greenish marly shale of these beds ; and it mentions as 

 among the fossils occurring in these ''washes" imperfect specimens 

 of Cyathocrinus, Platycrinus, Synbathocrinus , Actinocrinus , and 

 Forhesiocrinus (p. 122). 



In the Fifteenth Report, 1885-86, on the Geology of Washington 

 County, by Gorby (p. 124), it is very clearly shown that the Burling- 

 ton beds are represented by certain irregular buff to gray limestones 

 occurring between the shales and sandstones of the Kjiobstone and 

 other limestones and cherts in which Keokuk species prevail ; and he 

 says (p. 132): ''The tendency of the evidence leads strongly to the 

 conclusion that these beds of this (Burlington) group separate the 

 Keokuk from the KJnobstone throughout the greater portion of 

 Washington and Harrison Counties." In some locahties in these 

 counties red or buff limestone layers have yielded undoubted Upper 

 Burlington species; and in Washington Count}^ certain buff, geo- 

 diferous beds lying very close to the Knobstone shales contain a 

 characteristic Keokuk crinoid fauna, with many species identical 

 with those found at Indian Creek, in Montgomery County. 



It may be here remarked that little dependence is to be placed 

 upon color as distinguishing the Burlington and Keokuk beds in the 

 Indiana-Kentucky region; the one may be red and the other blue 

 at one place, and the colors exactly reversed a short distance away; 

 and colors of the same bed often change m short distances. In the 

 Burlington-Keokuk beds of the typical region along the Mississippi 

 River, which was a center of deposition with little disturbance, the 

 coloration is extremely regular and characteristic, and a person 

 whose early collecting was in these localities is apt to attach too 

 much importance to color elsewhere. The southern Indiana region 

 especially was one of many changes, and frequent invasions and 

 recessions of the waters, accompanied by much erosion and replace- 

 ment during the epoch which the Keokuk-Burling ton-Wars aw beds 

 represent; so that their tliickness is extremely irregular, and m 

 many places their vertical section is greatly reduced. Thus there 

 ;iiay be characteristic Burlington and Keokuk, or Keokuk and 

 Warsaw, fossils at the same exposure from a few feet of strata. 

 There have also been extensive later denudations cutting through 

 several beds of rocks, and redistribution of the material, with its 

 contained fossils, from one area to another, so that those from two or 

 three successive formations may be found together in the same bed 

 of clay. This is clearly stated in the last-mentioned report (p. 135), 

 and is borne out by the experience of every careful collector. For 

 instance, the well-known locahty of Spergen Hill, which name is 

 really applied to fossils collected over an area of several square miles 

 covered by a deposit of reddish ferruginous clays, containing the 

 94428°— Proc.N.M.vol.41— 11 12 



