THE OHIO VALLEY IN SOUTHERN INDIANA 271 



that the data from which it was made was incomplete in the 

 Mississippi embayment and so the coast line is very general. 



If these deposits are Lafayette it would seem that an arm 

 of the sea extended up the Ohio valley from the great Missis- 

 sippi embayment past Posey, Vanderburg, Warrick, Spencer and 

 into, if not past, Perry county, Indiana. In order to fully estab- 

 lish the size and shape of this embayment it would be necessary 

 to examine carefully all lands bordering the Ohio River on both 

 sides from Perry county, Indiana, to the mouth of the Wabash. 

 Figure 2 shows in a general way this supposed extension of the 

 embayment. 



The data collected throws some light on the history of the 

 Ohio valley at this point. This history is shown in Figs. 5, 6, 7, 

 and 8. In these no attempt has been made to show the exact 

 character of the rock bottom of the channel as the well sections 

 furnish no evidence on this point. It may be mentioned, as 

 having some bearing on the history, that a rock shelf comes out 

 from the base of the hills north of Enterprise and extends about 

 20 feet underground to the present river channel. Just across 

 the river wells are reported 60 feet deep and showing that here 

 as at Rockport there is a deep filled valley. 



During the pre-Lafayette period the land stood at about its 

 present level, and the Ohio River cut out the valley shown in Fig. 

 5. This period was followed by the Lafayette submergence 

 when the sands and gravels were laid down as an estuarine 

 deposit and the valley probably assumed about the appearance 

 shown in Fig. 6. 



During the post-Lafayette or Ozarkian period the land stood 

 more than 70 feet higher than now and the river after cutting 

 through the Lafayette sands and gravels cut deep into the under- 

 lying Carboniferous rocks (Fig. 7); cutting from side to side it 

 took away the Lafayette gravels in places along the side of the 

 river leaving deposits only here and there. Then followed 

 another subsidence and the river filled up its channel making a 

 broad alluvial flood plain. At some time after the post-Lafayette 

 high level the loess was deposited on the bluffs on either side 



