PUBLICATIONS. 105 
exist in them, but in the most northern areas of the Lafayette, as shown 
by numerous exposures, glacial material has been shown to be absent. 
This is no more than negative evidence against the Pleistocene age of 
the Lafayette; but the volume of negative evidence is so great that it 
has carried conviction to every geologist, so far as we know, who has 
studied critically both the glacial drift and the Lafayette formation. 
Concerning the origin of the Lafayette, Dr. Smith appears to 
incline to the view which has been advocated by McGee, viz., that the 
Lafayette materials were deposited during submergence of the region 
which they cover. In this connection a new suggestion is made concern- 
ing the relation of the third terraces noted above, to the body of the 
Lafayette. The suggestion is that in the emergence of the land on 
which the Lafayette had been deposited, the rivers lowing down over 
it brought in new material from the north, in this way, perhaps, adding 
aland accumulation to the marine accumulation which had already 
been made. It is suggested further, that in the course of time these 
streams came to be confined in more or less well-defined valleys of 
their own development, and that at some stage during the uplift, there 
was a halt of such duration that the broad valleys which these streams 
occupied were filled up by the streams to the level of the third ter- 
races. This would make the third terraces ‘‘the last episode of the 
Lafayette drama.” As the valleys were filled, the coarse materials 
lodged first, and the fine later, thus giving the relations which are 
found to exist.. Dr. Smith points out very distinctly that these third 
terraces of Lafayette-like material do not grade into the second ter- 
races, as has sometimes been supposed. 
A good deal that is new appears in connection with the Miocene. 
Two distinct divisions of the Miocene are recognized. ‘The uppermost 
is the Pascagoula, which has a thickness of something like two hun- 
dred feet. It is composed mainly of clays, with more or less green 
sand. Below this lies the Grand Gulf formation, the age of which has 
been definitely fixed as lower Miocene. 
The data of this report concerning the Eocene have been largely 
published before in Bulletin 43 of the United States Geological Survey. 
The present report proposes some modifications in the classification 
there given, and publishes some new facts, the result of recent field 
work. 
The average seaward dip of the Tertiary formations is said to be 
twenty-five to thirty feet per mile. Even these young and, on the 
