E. D. McEwan — Ordovician of Indiana. 155 



Between the elevations of 77 and 83 feet shale and 

 shaly limestone predominate. Rafinesquina and other 

 broad flat fossils are found here in an edgewise position 

 at an elevation of about 75 to 80 feet. 



The rocks which occur between 89 and 135 feet are 

 found in the upper part of the ravine and the lower part 

 of the railroad cut. They consist of heavy limestone and 

 argillaceous limestone varying from an inch to 10 feet 

 in thickness and separated by shale layers. 



Between 135 and 172 feet above the base of the section 

 are brown weathered layers of limestone and shale. 

 These occur in the uppermost part of the ravine and in 

 the railroad cut. The upper 30 feet of the section con- 

 sist of heavy limestone layers separated by shale. 



Bellevue. 



The lowest exposure of this division is in the creek at 

 the foot of the gully at a point several hundred feet 

 down stream. The Bellevue is also beautifully exposed 

 in a quarry in the eastern part of Madison. It is very 

 fossiliferous, containing great numbers of individuals 

 representing each species. The common forms are Plat- 

 ystrophia ponder osa (Foerste), P. unicostata (Cumings), 

 P. unicostata crassaformis (McEwan), Hebertella sinu- 

 ata (Hall), Rafinesquina alternata (Emmons), Monti- 

 culipora molesta (Nicholson), Bythopora gracilis 

 (Nicholson), Hallopora ramosa (D'Orbigny,) and Homo- 

 try pella dubia (Cumings and Galloway). 



The f aunal evidence in the exposure 20 to 27 feet above 

 the lowest outcrop seems to suggest a gradual change 

 from Bellevue to Corryville time. A few new species, 

 such as Dekayia appressa Ulrich and Cyclonema simu- 

 lans Ulrich, suggest an invasion of the area possibly by 

 the lowering of some barrier. The fauna is on the whole 

 very similar to that of the underlying Bellevue. This 

 part of the section is located along the creek at the foot 

 of the hill below the south cut. 



Corryville. 



In the next 50 feet Corryville species become more 

 prominent. ChiloporeUa flabellata (Ulrich), Dekayia 

 appressa (Ulrich), Platystrophia laticost l a (Meek), and 

 Eridotrypa simulatrix (Ulrich), are common. The 



