. Maryland geological survey. nizing the locality and little need be added to his original de-scription. He made a sharp distinction between the fossil-bearing claysbelow and the unfossiliferous cross-bedded gravel and sand above. Healso drew attention to the fact that the fossils had a very recent aspectand many of them were identical with living forms inhabiting theshore of the United States, and as they were sub-fossilized, theyresembled some of the more recent formations of the West Indies. Twoyears later Conrad made an attempt to sub-divide the surficial depositswhich he had previously de
. Maryland geological survey. nizing the locality and little need be added to his original de-scription. He made a sharp distinction between the fossil-bearing claysbelow and the unfossiliferous cross-bedded gravel and sand above. Healso drew attention to the fact that the fossils had a very recent aspectand many of them were identical with living forms inhabiting theshore of the United States, and as they were sub-fossilized, theyresembled some of the more recent formations of the West Indies. Twoyears later Conrad made an attempt to sub-divide the surficial depositswhich he had previously designated by the general term separated them into Diluvium which he described as composed ofsand, clay, and rounded fragments of rock containing remains of largequadrupeds and deposited without order or arrangement by violentcurrents. He correlated it with the Gravier coquillier or Crag. Themore modern aspects of the surficial cover he called Alluvial and MARYLAND GEOLOGICAL SURVEY PLIOCENE AND PLEISTOCENE PLATE II. MARYLAND GEOLOGICAL SURVEY 29 defined it as all deposits derived from causes now in operation, suchas accumulations of mud along river courses, drifting sand, peat-bogs, few years later, in 1839, he came to the conclusion that the hugeangular blocks in the Diluvial were transported and deposited thereby glaciers or icebergs. While Conrad was still engaged in studying the Coastal Plain forma-tions, Ducatel and Alexander began the publication of a series of Statereports which covered the period between 1834 and 1839. Alexander wasengaged in the engineering phases of the work, while Ducatel devoted histime to geological investigations. As his attention was directed more tothe economic side of geology, he gave his efforts to the iron ore-bearingclays of the Potomac beds and the shell and marl deposits of the Tertiaryformations, and paid little attention to the overlying surficial deposits ofloam, sand, and gravel. He, therefore, added very little to the
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