309] G. E. Dorsey 111 



greensand." This is true to a marked extent for only the 

 beds along Bohemia Creek in Maryland, in the northeastern 

 part of the state. The Monmouth, as it occurs on the West- 

 ern shore of the state, from Anne Arundel to Prince George's 

 county, has lost the markedly glauconitic character of the 

 Bohemia Creek facies, clays and muds being considerably 

 more prominent. It is especially significant, in view of the 

 above, that we find B. americana in abundance on the Eastern 

 shore in the glauconite, and no trace of it on the Western 

 shore in the muds and clays. 



Weller (22, p. 18) has called attention to the fact that the 

 Eedbank sands of New Jersey pinch out passing to the south- 

 west, their stratigraphic position being occupied by the Nave- 

 sink marls which here still maintain their glauconitic facies. 

 Accordingly, as one progresses toward Delaware and Mary- 

 land from Long Island, he passes through a series that is 

 progressively more glauconitic, until over southwestern New 

 Jersey, Delaware, and northeastern Maryland is located the 

 greatest development of this facies. Still farther toward the 

 southwest, the greensand aspect gives way to muds and clays, 

 until one reaches the Virginia land mass. This points pretty 

 definitely to the existence of a basin in which glauconite was 

 being deposited, far enough removed from land, or with such 

 a slight influx of terrigenous materials, as to give clear, quiet 

 waters, during a large part of Monmouth time. 



As noted above, Virginia was above water during the Mon- 

 mouth, but in North Carolina, in the so-called Peedee sands 

 of Ruffin, we have conditions of sedimentation almost iden- 

 tical with those of the New Jersey-Delaware-Maryland Mon- 

 mouth, a series of alternating sands and clays, the sands 

 being highly glauconitic. According to Stephenson (8, p. 

 146), "The content of glauconite in the greensands of North 

 Carolina appears to be less than that of the greensand marls 

 of New Jersey." A careful study of the sections of those 

 localities at which B. americana is found, reveals, without 

 exception the highly glauconitic nature of the fossil-bearing 



