of the Lafayette Formation. 395 



both in and around its area of occurrence. I am not however, 

 prepared to discuss the eastern phase of the formation, of 

 which I know merely generalities. From statements made by 

 McGee 1 infer that there are wide and material differences in 

 the maximum elevation at which the formation is found at 

 various points around the Appalachian highlands ; the data thus 

 far published by him are not sufficient for an outside discus- 

 sion of this point. 



In the Embayment itself, some questions arise in regard to 

 the identity of the formation as a whole, since McGee inclines 

 to consider as belonging to it a lower phase of "plant beds" 

 which I have always regarded, and do still regard, as belong- 

 ing to the subjacent formations of various ages. Nothing that 

 I have seen during the late joint reconnoissance seems to me to 

 justify a change of opinion on my part in this respect ; I have 

 now as formerly seen the lignitiferous beds of the several stages 

 of the Tertiary, from the lowest Eo-lignitic to the Grand Gulf, 

 underlying the characteristic transition beds of the "Orange 

 Sand ; " but I hope to be able to set this question at rest by a 

 microscopic examination of the specimens collected. If there 

 is any true " Lafayette " plant bed, it should be possible to 

 identify it at the various points of occurrence ; which to my 

 mind, however, exhibit simply contact phenomena. Prof. 

 Ward's paleobotanic researches, also, will I hope be brought to 

 bear on this question. I understand, however, that McGee 

 does not claim such a plant bed as an integral part of the 

 Eastern phase of the formation. Its existence would not neces- 

 sarily conflict with either his or my views of the origin of the 

 Lafayette sands. 



One of the most vital points to be settled by closer investi- 

 gation than has yet been made is the exact correlation of the 

 gravel deposits. From their apparent continuity I have re- 

 ferred to the Lafayette age most of the larger gravel beds of 

 the interior and river border, distinguishing only those mani- 

 festly belonging to the surface loam, and certain limited 

 deposits within the Port Hudson beds. McGee has shown 

 that small gravel beds do occasionally occur at the base of the 

 Loess itself ; and a late detailed examination of the instructive 

 profile at Natchez proved, to the satisfaction of all of the 

 exploring party, that even considerable gravel beds do occur 

 within what, from all characters, must be presumed to be Port 

 Hudson beds. Within these I found several small crystalline 

 (gneissic and mica-schist) pebbles ; but it was in a bed of fer- 

 ruginous gravel conglomerate of some 25 feet thickness, under- 

 lying the typical Port Hudson and reaching below water 

 level, that an abundance of crystalline pebbles, and cobbles up 

 to three and four pounds weight, were found. It was proba- 



