Maryland Geological Survey 39 



Journal of Science entitled Notes on the Mesozoic of Virginia, and in- 

 cluding the Triassic in his discussion. The flora received considerable 

 attention and the materials were grouped into the " Fredericksburg belt " 

 and the " Petersburg belt/' the one corresponding with what he after- 

 ward called the Fredericksburg beds and the other answering to the 

 James River beds, both in large part referable to the Patuxent forma- 

 tion. It was in the part published in the February number of the Ameri- 

 can Journal of Science that the " archaic dicotyledons " of the Potomac 

 were first mentioned in the following language : " With the plants above 

 named, I find certain netted veined leaves, which by their nervation can- 

 not be distinguished from Angiosperms. Had they been found with 

 Cretaceous or Tertiary plants I think no one would hesitate to consider 

 them as such. As, however, they occur with a well-marked upper Juras- 

 sic flora, I hesitate to pronounce them to be Angiospermous plants with- 

 out a more careful study and extended comparison than I have as yet 

 been able to make. They are certainly not ' Dictyophyllum,' which is 

 the genus of fossil ferns that stands nearest to them. But when we find 

 such a development of undoubted Angiosperms in the lowest Cretaceous 

 beds of New Jersey and of the west, we should expect to find at least their 

 ancestors in the Jurassic flora," Further along he speaks of the evidence 

 as to the age of the iron-ore clays as pointing strongly to the conclusion 

 that they were Wealden. 



In a lecture by Professor Uhler, an abstract of which was published in 

 1883, considerable space was given to what is now regarded as part of the 

 Potomac Group, and which he calls Upper Jurassic or Wealden, gi\ing 

 it a thickness of 500 feet in the Baltimore region. 



In the spring of 1884 Professor Ward prepared a short paper on 

 Mesozoic Dicotyledons, in which he mentions Fontaine's archaic dicotyle- 

 dons, which he states are from the Upper Jurassic of Virginia, and ex- 

 presses the hope that the problem of the origin of this group is at last 

 approaching solution. About this time Professor Fontaine joined the 

 staff of the U. S. Geological Survey, his first administrative report ap- 

 pearing in 1885 in the Sixth Annual Report. 



In 1886 the name Potomac formation first appeared in print in a paper 



