360 MESOZOIC FLORAS OF U^^ITED STATES. 



During this reconnaissance the formation was constantly looked upon 

 as a single geological unit with no presumed difference between its land- 

 ward and its coastward margin, and it was often spoken of as a "trough" 

 and compared to the Triassic beds farther inland. But before the 

 expedition ended I suspected that this was not the case, and that the 

 formation consisted of a series of beds of different age, those of the coast- 

 ward side being younger than those of the landward side, and that these 

 beds regularly ran under the overlying marine deposits. Among the facts 

 pointing to this conclusion was the occurrence at Deep Bottom (called 

 "Deep Hole" by Rogers"), the most easterly point on James River, of 

 dicotyledons of higher and more modern types than the archaic ones of 

 other beds. Also in the railroad cutting below Aquia Creek, and especially 

 in a bank near this place, discovered by me, large numbers of leaves of 

 unquestionable dicotjdedonous type, afterwards mostly referred to the 

 genus Sapindopsis Font., as perhaps related to the soapberry, were col- 

 lected, and these beds are immediately overlain by the Eocene. More than 

 this, our investigations on the Severn River revealed other and still 

 higher types, resembling those of the Amboj' clays. 



Correspondence with Professor Fontaine was kept up during the fall 

 and winter, and in one of his letters, dated February 12, 1886, he remarks: 



I do not think that I have ever told you about the collection I made at Brooke 

 station after we parted. I am working up that material, and having looked care- 

 fully over all of it I can now give the results. This is the last of the material that 

 I have on hand to study, and when I finish it I could take up Doctor Newberry's 

 plants and bring the work to a close. 



I collected both in the railroad cut and from the bank first discovered by you. 

 I was disappointed in not tinding a number of new species of angiosperms, for nearly 

 all of the impressions are of the pinnatelj' compound leaf previous^ found. A 

 multitude of these impressions were found, and among them a number of depar- 

 tures from the normal form. I found several new species of conifers and ferns, and 

 several of the forms common at other localities in the Potomac terrane. Before I 

 made this last collection I was troubled by the fact that at this locality, yielding 

 unquestionable angiosperms, the other plants were in the main peculiar to tliis spot, 

 and no forms like those" occurring elsewhere and having a Jurassic type were seen. 

 Although the stratigraphy and lithology indicated that the Brooke beds are of the 

 same age as those of Fredericksburg and Dutch Gap, the possibility would obtrude 

 itself that the flora here is younger than that found elsewhere. 



« Report for 1840, p. 31. 



