MARYLAND GEOLOGICAL SURVEY 55

A work of some importance in its day was " An elementary treatise
on Mineralogy and Geology, " which was published by Parker Cleave-
land in 1822 and in which frequent references are found to Maryland
minerals. Maclure's map of the United States is reproduced in the
volume.

One of the most important contributions to the stratigraphy of the
Coastal Plain which had up to that time appeared, was made by
Professor John Finch in a " Geological Essay on the Tertiary Forma-
tions in America, " in the American Journal of Science and Arts for
1824. ¹ This was the first attempt at a correlation of the deposits of
the Coastal Plain on scientific grounds, and although thus early in
the history of the subject, minute comparisons, which are always un-
satisfactory, were made, yet the knowledge of the Maryland Tertiary
formations was materially advanced. In this article Professor Finch
objects to Maclure's use of the term " alluvium " and shows that the
formations so called are " contemporaneous with the newer Secondary
and Tertiary formations " of other parts of the world.

During the same year Thomas Say of Philadelphia presented " An
Account of some of the Fossil Shells of Maryland, " in which he
describes and figures many new species, although he draws few geo-
logical inferences from the organic remains examined.

Another contribution of some moment is " An Account of the
Examination and Surveys, with Remarks and Documents Relative to
the Projected Chesapeake and Ohio, and Lake Erie Canals, " which
was published by James Shriver in Baltimore in 1824. This pamphlet
includes remarks on the minerals and rocks of the area traverse'd.

In Robinson's " Catalogue of American Minerals, with their locali-
ties, " published in Boston in 1825, several pages are devoted to Mary-
land minerals.

" The shell marl region of the eastern parts of Virginia and
Maryland "² was discussed by James Pearce in the American Journal
of Science for 1826, the now historic locality of Marlboro being
described.

¹ Vol. vii, pp. 31-43. ² Vol. xi, pp. 54-59.