Ripley Island Area of Southern Indiana. 329 



banded rock of earlier surveys, formerly believed to correspond 

 to the Medina of New York. 



At the top of the Madison section is a peculiar bluish lime- 

 stone weathering in a very irregular manner, and containing a 

 considerable fauna which has been only partially studied. 

 Among other fossils may be mentioned Cyrtocerina madison- 

 ense, Orthooeras several species, Iscliyrodonta truncata, Ischy- 

 rodonta cf. miseneri, Ctenodonta simidatrix, Rhytima sp. 

 near oehana in size, Byssonyohia several species, lophospira 

 hammelli, liospira, Ilolopea huhhardi, labechia ohioensis, 

 and various species of ostracoda. 



On tracing the Madison bed northward from Madison 

 the massive coral bed at the base does not prove to be a con- 

 spicuous feature for any great distance, nevertheless in an 

 inconspicuous form it proves constant to its proper horizon as 

 far north as Osgood at least. Here along the stream following 

 the old line of the Baltimore and Ohio Southwestern railroad, 

 about two miles northeast of the town, specimens of Columnaria 

 alveolata- are rather common immediately below the beds con- 

 taining Tetradium • Hebertella insadpta, marking the base of 

 the Liberty bed, occurs just below the junction of this stream 

 with Laughery creek, with the normal vertical interval. At 

 Versailles, however, specimens of Columnaria alveolata are 

 rather rare, though some of large size are found occasionally at 

 the proper horizon. 



The Tetradium bed, on the contrary, often gains in import- 

 ance northward. At Versailles its thickness is eight and a half 

 feet, Columnaria alveolata occurring 16 inches lower down. 

 At Osgood, it rests immediately upon the Columnaria alveo- 

 lata bed. At the Derbyshire Falls, southwest of Laurel, the 

 Tetradium bed has a vertical thickness of three and a half 

 feet; Hebertella inseulpta, marking the base of the Liberty 

 bed, occurs at the proper vertical interval along the road lead- 

 ing from Laurel to Metamora, a short distance south of the 

 crossing over the stream which flows from the Falls to the 

 river. 



At Madison, and southward along the Ohio river, the most 

 characteristic part of the Madison bed is the massive sandy brown- 

 ish rock, 32 feet thick, forming the upper two-thirds of the 

 section. This phase continues northeastward from Madison 

 across the eastern half of Jefferson county. Northwest of this 

 line, however, toward Versailles, New Marion, Butlerville, and 

 northward, there is a considerable change in the lithological 

 appearance of this part of the Madison bed section. The first 

 change is seen 5 miles north of Madison, at the crossing of Razor 

 creek over the Graham road ; here the upper part of the sec- 

 tion equivalent to the massive brownish sandy bed is more 

 whitish, more calcareous, and less sandy. Two miles farther 



