MARYLAND GEOLOGICAL SURVEY 109

publication entitled " Artesian Well Prospects in the Atlantic Coastal
Plain Region. "¹ The chapter on Maryland occupies pages 124-155,
with maps and sections.

In 1894-95 and 1895-96 Mr. Darton made occasional trips in Mary-
land, mainly for the purpose of obtaining final data for the Wash-
ington folio. He also differentiated the Pleistocene formations into
" earlier Columbia" and " later Columbia, " and ascertained their
geologic history. Some of the results of this investigation were
set forth in " An outline of the Cenozoic History of a Portion of the
Middle Atlantic Slope. " ²

In 1896 a map showing the distribution of the Potomac formation
in Maryland and Virginia was prepared for Professor Fontaine's
paper on the Potomac formation. ³

During 1896 much work was done upon the Cretaceous formations
of Maryland and Delaware by Dr. Clark and his assistant, Dr. Bagg,
partly under the auspices of the United States Geological Survey and
partly under those of the Maryland Geological Survey.

Much attention has been given by the United States Geological
Survey to the paleobotany of the Potomac formation. Professor W.
M. Fontaine made extensive observations and collections in Virginia
in 1886 and 1887, and examined some localities in its northern ex-
tension as far as Baltimore. Fossil plants were also obtained in Bal-
timore by Professor Ward in 1886 and forwarded to Professor Fon-
taine for study. The publications by Professor Fontaine are a mono-
graph on the " Potomac or Younger Mesozoic Flora "⁴ and a bulletin
recently issued entitled " The Potomac Formation in Virginia. " ⁵
Both of these publications relate in some measure to the Potomac
formation in its extension into Maryland.

The studies by Professor L. F. Ward of the Potomac formation
and its flora began in the summer of 1885 with a trip with Professors
McGee and Fontaine along the formation in Virginia and Maryland.

¹ Bull. U. S. Geol. Survey No. 138, 1896.

² Jour, of Geology, vol. ii, pp. 568-587.

³ Bull. U. S. Geol. Survey No. 145, 1896, pl. 1.

⁴ Mon. U. S. Geol. Survey, vol. xv, 1889, 377 pp., 130 pls., 4°,
⁵ Bull. U. S. Geol. Survey No. 145, 1896, 149 pp.