DISTKIBHTION OK TllK WAI.DUON FAUNA. 4:04 



the Devoniau. Mr. Prices evidently held this opinion with refer- 

 once to the immediate vicinity of Greensburg, since he states ''The 

 Waldron shale is absent and was probably never deposited in this 

 locality." The important fact for our present purpose, which this 

 map shows, is that for a distance of about 30 miles along its 

 eastern border the Waldron shale and the Louisville limestone are 

 overlapped by the Devonian limestone. It appears highly improb- 

 able that erosion during the Devono-Silurian unconformity inter- 

 vals would have completely removed both formations to the east 

 of the Devono-Silurian parting and left them both with rather 

 slight evidences of erosion a short distance to the west of that 

 boundary. 



Composition and Distribution of the Waldron Fauna. 



The luxuriant fauna which characterizes the Waldron shale at 

 Waldron retains a considerable number of the 160 odd species 

 known at Waldron for fifty miles south of this place. Paris Cross- 

 ing and Dupont are the most southerly localities at which the fauna 

 retains its characteristic richness in the number of species and 

 individuals. South of the Big Creek locality, near Dupont, the 

 fauna is still represented, but in a depauperate condition. At Han- 

 over, on the Ohio River, less than half a dozen species have been 

 found to represent the rich fauna at Hartsville and Waldron. At 

 many localities near the Ohio, it appears to be almost if not quite 

 barren of fossils. While all the outcrops of the Waldron within 

 25 miles of the Ohio are but very slightly fossiliferous it should be 

 observed that numerous nearly barren outcrops occur also in the 

 same general region as the richly fossiliferous exposures. These 

 semi-barren localities so far as noted seem to lie to the east of the 

 highly fossiliferous ones. It may be that the faunal poverty of 

 these outcrops, together with those near the Ohio River, is due 

 to the fact that they represent an in-shore zone lying slightly to 

 the east of the belt most favorable to the growth of a luxuriant 

 fauna. Shallower water, a slightly different temperature, or differ- 

 ence in salinity may have made the extreme in-shore zone unfavor- 

 able to the rich fauna living just outside it. That all of the Wal- 

 dron outcrops near the Ohio would belong to this more easterly 

 belt follow^s from the fact that the greater westerly dip near the 

 river reduces the width of the outcropping belt of the Silurian rocks 

 from 30 miles or more near Waldron to 10 miles or less from Jef- 



" Ibid., 3, p. 89. 



