The Rogers Gap Fauna of Central Kentucky IIS 



ward of the line indicated, so that it is difficult to identify the same 

 horizons north of Lexington, especially between Georgetown and 

 Rogers Gap, and along the line from Cynthiana to Cincinnati, or 

 along the Ohio river east of Ivor. The strata here are much more 

 argillaceous and present a different faunal aspect, although the 

 Greendale member, as developed near Lexington, is regarded as 

 the approximate equivalent of the much more richly fossiliferous 

 Millersburg limestone farther eastward. 



B. Rogers Gap to Sadieville. 



The exposures along the railroad immediately south of Rogers 

 Gap, and from this point northward as far as Sadieville, are re- 

 garded as belonging above the horizon of the ]^lillersburg or Ortho- 

 rliyuchula horizon. They have already furnished a number of fos- 

 sils of interest to science. Among these are Fiisispira sulcata^ 

 described by Llrich in the third volume of the Minnesota Geolog- 

 ical Survey ; Hetcrotrypa focrstci, described by Xickles in Bulletin 

 5 of the Kentucky Geological Survey; and Eridorthis rogcrsensis, 

 Eridorthis uicklcsi, and CUtainhonitcs rogcrsensis, described in 

 volume Fourteen of the Bulletin of Denison L'niversity. To this 

 list must be added Strophoincua higginsportensis, described in 

 volume Seventeen of this Bulletin from strata along the Ohio 

 river, now known also from the exposures north of Rogers Gap. 

 This Rogers Gap Fauna is, in manv respects, peculiar, including 

 species not found at any other horizon. This fauna forms the 

 object of special study on the following pages. The typical ex- 

 posures, extending along the railroad from the cut immediately 

 south of Rogers Gap to that north of the bridge north of Sadie- 

 ville, have been selected. An account of the relationship of the 

 various strata here exposed follows. 



Immediately south of the railroad station at Rogers Gap, there 

 is exposed, a short distance above track level, a coarse-grained, 

 massive limestone, above which lies the typical Rogers Gap fauna 

 as found in the railroad cut farther southward. A third of a mile 

 north of Rogers Gap this massive coarse-grained limestone is ex- 

 posed again, west of the track, below railroad level. It is seen 



