31 The Upper Cretaceous Deposits of Maryland 



HISTORICAL REVIEW. 



The Upper Cretaceous formations of Maryland were not generally 

 recognized as such until a very late period in the investigation of the 

 Atlantic Coastal Plain strata. Even after the Cretaceous age of the 

 lower part of the deposits had been recognized they were associated with 

 the underlying beds which were commonly regarded as Lower Cretaceous, 

 or even in part as Jurassic. The upper beds of the series were, on the 

 other hand, often associated with the overlying Eocene deposits with 

 which in certain places they present much similarity in lithological 

 character. It was not until a relatively recent period that the Upper 

 Cretaceous age of the greater part of these deposits was recognized. 



Some of the earlier American geological writings refer in a general 

 way to the territory under discussion. William Maclure in his " Obser- 

 vations on the Geology of the United States, explanatory of a Geological 

 Map," in 1809 mentions the region, although in this publication the entire 

 Coastal Plain is referred to the " alluvial formation," the fourth of the 

 grand divisions of the geological column according to the Wernerian 

 classification which Maclure adopted. 



Another early publication in which the district under discussion was 

 mentioned is that of H. H. Hayden entitled : " Geological Essays : or an 

 Inquiry into some of the Geological Phenomena to be found in various 

 parts of America and elsewhere." This early publication by a Maryland 

 man was published in Baltimore in 1820. 



Gerard Troost in 1821 discusses the occurrence of amber on the 

 Magothy River in Anne Arundel County in deposits now referred to the 

 Magothy formation. In this article the author refers to the geological 

 occurrence of the amber and to the associated minerals and fossils. 



By far the most important contribution to the stratigraphy of the 

 Coastal Plain that had up to that time appeared was made by John 

 Finch in his " Geological Essay on the Tertiary Formations in America." 

 This was the first attempt to correlate the deposits of the Coastal Plain 

 on scientific grounds, and although many comparisons of doubtful value 

 were made, yet the knowledge of American Coastal Plain formations was 



