MARYLAND GEOLOGICAL SDEVET 31 



no better than that published by the United States Coast and Geodetic 

 Survey, but while the former confined its efforts mostly to the water- 

 ways and mapped the adjacent land only a mile or two from the coast, 

 the United States Geological Survey mapped the entire land area. The 

 map was printed in three colors, blue, brown, and black. The hydrography 

 was represented in blue and went into great details, including not only 

 the larger water-ways, but also the smaller streams and their minute 

 branches. Relief was represented by contours with a 20-foot interval 

 and printed in brown; while the culture, inckiding highways, bridges, 

 railroads, houses, and the names of important localities, was printed in 

 black. 



The present Maryland Geological Survey, in co-operation with the 

 United States Geological Survey, revised this map in the year 1900, and 

 it is on this base that the geologic formations of the county have been 

 mapped. 



THE HISTORY OF GEOLOGIC RESEARCH.'' 



From an early date the attention of geologists has been attracted to 

 St. Mary's County. The reason for the great interest in this region is 

 probably due not only to the extensive deposits of fossil beds which are 

 found within its borders, but also to the fine and continuous exposure 

 which is found along the Bay shore and the banks of the Patuxent and 

 St. Mary's rivers. The observations which were made led to con- 

 clusions which, in the early days of geologic research, were vague and 

 oftentimes erroneous; but as time advanced and the principles 

 underlying geologic history have become better understood, the papers 

 which have been contributed on the region have become more satisfactory 

 and the work more explicit and meritorious. As in the geographic re- 

 search, so in the geologic, the evolution has been from the vague and 

 general to the detailed and specific. 



° Many of the broad generalizations of the early investigators in southern 

 Maryland apply to the entire region although specific localities are seldom 

 mentioned. In preparing this historical sketch, it has been necessary to 

 refer to these papers although few of them mention the name of St. Mary's 

 County. 



