L86 R. I). SALISBURY EXTENSION OE ERE-PLEISTOCENE GRAVELS. 



Subsequent to my own first determination of the existence of these 

 gravels above the mouth of the Illinois river it was found that Professor 

 Worthen had already noted their existence in Hancock* and Pike f 

 counties and had correlated them, as I think rightly, with similar gravels 

 farther southward .J 



The extension of these pre-Pleistocene gravels northward docs not 

 appear to be their only one. To the eastward as well they have a greater 

 extension than has heretofore been known, so far as I am aware. They 

 have been found in Gallatin county, Illinois, near the Wabash river. 

 This is the only point in eastern Illinois north of the Big Bay Cache 

 valley (an old course of the Ohio) where they are known to occur. These 

 gravels have their easternmost extension, so far as now known, near Tell 

 City, Perry county, Indiana, where there are very considerable beds 

 identical in all essential features with the gravels of the Mississippi valley. 



In the Ohio valley, as in the Mississippi, gravel which belonged origi- 

 nally to the same formation has been recognized in the drift and has been 

 seen in secondary positions many miles east of Tell City. It may, there- 

 fore, be confidently affirmed that this locality does not represent the 

 original eastern limit of the formation, although it is many miles east 

 of any locality north of the Ohio heretofore known to the writer to be 

 characterized by these gravels. 



*Geol. Survey of III., vol. i, 1866, p. 331. 

 fGeol. Survey of 111., vol. iv, 1870, p. 37. 



JiSome years previously similar gravels wore described by McGee from northeastern Iowa (Geol. 

 Mag., new series, decade ii, vol. vi, pp. 3.",."), 360). 



