66 HISTORICAL SKETCH

W. B. Rogers, that of Pennsylvania in 1836 under H. D. Rogers,
and that of Delaware in 1839 under J. C. Booth. The investigations
carried on by these surveys along the borders of Maryland were of
much importance in deciphering the geological structure of the forma-
tions of Maryland as well. The work of the Rogers particularly, to
the north and south of Maryland, had an important bearing upon the
development of knowledge regarding the geology of the state of Mary-
land, and the results of their work are still frequently employed by
those seeking information regarding the geological structure of our
own state.

AN ACCOUNT OF BOTH PRIVATE AND OFFICIAL INVESTIGATIONS

CONDUCTED AFTER THE TERMINATION OF THE FIRST STATE

GEOLOGICAL SURVEY TO "THE OUTBREAK OF THE

CIVIL WAR.

INVESTIGATIONS CONDUCTED UNDER OTHER THAN STATE AUSPICES.

The termination of the first geological survey was followed by a
period of little activity in geological work. From time to time in-
vestigations were made, under private auspices, of special phases of
Maryland geology, but little systematic work was undertaken. The
most marked exception to this general rule is seen in the continued
work of Dr. T. A. Conrad, who pursued his investigations upon the
Tertiary deposits of the country, and almost yearly contributed
articles in which both the Eocene and Neocene faunas of Maryland
received greater or less attention. The publications of Dr. Conrad
during this period are perhaps the most important contributions that
were made to Maryland geology.

The visit of Charles Lyell to America during the early portion of
this period had an important influence upon the development of
knowledge regarding the geology of the country. Although his
observations extended over a wide area from New Jersey to the Gulf,
his conclusions were nevertheless of much value to each region,
especially in the Coastal Plain. On account of his wide knowledge of
the Cretaceous and Tertiary in other portions of the globe, he suc-
ceeded in explaining many points hitherto imperfectly understood in