MARYLAND GEOLOGICAL SURVEY 87

Ilchester, Howard County, Maryland; being a detailed study of the
area comprising Sheet No. 16 of the Johns Hopkins University map. "¹

The wider generalizations of Professor Williams found expression
in 1888 in two articles that were published under the auspices of the
University, the first, entitled " Geology of the Baltimore Region, "
was a report of a lecture in which the author referred to the sequence
of the eruptive rocks in the area discussed. Another article, on the
" Progress of Work on the Archean Geology of Maryland, "² appeared
about the same time, in which a sketch of Maryland geology is given
and the relations of the gneisses and eruptive rocks in Baltimore are
shown.

The work of Dr. Clark upon the sedimentary formations of the
southern portion of the state led the same year to the discrimination
of the marine Cretaceous deposits of that area. An article entitled
" Discovery of Fossil-bearing Cretaceous Strata in Anne Arundel and
Prince George Counties, Maryland"³ was published in 1889.
Further " Contributions to the Mineralogy of Maryland "⁴ were made
by Dr. Williams somewhat later in the season.

During this year two students of the Geological Department con-
tributed articles upon the mineralogy and geology of the crystalline
rocks, the contribution of Mr. A. C. Gill being entitled " Minerals
from the Chrome Pits of Montgomery County, Maryland, " ⁵ and that
of Mr. W. H. Hobbs " On the Paragenesis of Allanite and Epidote as
Rock-forming Minerals. " ⁶

The organization of extended expeditions for the study of the
geology and physiography of tidewater Maryland and Virginia had
been undertaken by Dr. Clark soon after his connection with the Uni-
versity. His report upon the " Third Annual Geological Expedition
into Southern Maryland and Virginia "⁷ describes the geological sec-
tion of the Potomac river valley in Maryland and Virginia.

¹ Johns Hopkins Univ. Circ. No. 65, vol. vii, 1888, pp. 69-70.

² Johns Hopkins Univ. Circ. No. G5, vol. vii, pp. 61-63.
^s Johns Hopkins Univ. Circ. No. 69, vol. viii, pp. 20-21.
⁴ Johns Hopkins Univ. Circ. No. 75, vol. viii, pp. 99-100.
⁵ Johns Hopkins Univ. Circ. No. 75, vol. viii, p. 100.
⁶ Amer. Jour. Sci., 3 ser., vol. xxxviii, 1889, pp. 223-228.
⁷ Johns Hopkins Univ. Circ. No. 81, vol. 9, 1890, pp. 69-71.