MAKYLAND GEOLOGICAL SURVEY 31 



and that the deposit of gravel, sand, and loam now found in Cecil county 

 was brought in by the flooded waters of the Delaware and re-worked by 

 the waves of the Atlantic Ocean. He, therefore, makes the gravels which 

 cover the hilltops and rest in the valleys of Cecil county of one age. 

 He also regards the deposits around Snow Hill, Maryland, as belonging 

 to his Estuary sand epoch. While Chester was publishing the results of 

 his studies, W. B. Eogers made an interesting suggestion in that he 

 pointed out that there was evidence of an ancient coast line along the 

 contact between the Piedmont and Coastal Plain regions or approximately 

 in the position of what we now know as the " fall line." Chester had 

 the same year, 1884, attempted to establish the shore line of the ancient 

 sea which deposited the gravels in Cecil county and had gone so far as to 

 construct a map showing the distribution of the gravels. As he made all 

 the gravels of one age, he was obliged to seek his shore line near the 

 western margin of the highest of the gravel series and, therefore, was 

 attempting to discover the shore line of the Lafayette sea. Eogers, on the 

 other hand, was referring to a shore line which was of much later age, 

 belonging well within the Pleistocene period. These two references are 

 most interesting as they are the first suggestions in literature of shore 

 lines in the Coastal Plain deposits. 



While Chester was at work on the surficial deposits along the north- 

 ern border of Mar}dand, Professor W J McGee had been studying the 

 same formations farther to the south. His field of observation was 

 much wider than that of Chester and although many of the conclusions 

 at which he arrived have been modified by later study, yet it must be 

 remembered that McGee laid the foundation for future work and prose- 

 cuted his studies wholly without the aid of contour maps which are 

 so essential and indispensable in unravelling the various formations of 

 the Lafayette and Columbia groups. McGee announced the results of 

 his investigations in a series of articles which appeared between the 

 years 1886 and 1889. As they, in a large measure, depend one on the 

 other, they will not be considered separately, but his general conclusions 

 will be discussed as a whole. According to McGee the Lafayette formation, 

 which was described as a series of orange-colored loams, sands, and 



