1890] MARYLAND ACADEMY OF 8CIENCES. 101 



Aisquith's Creek, the upper 25 feet of this member is distinctly 

 indurated, is highly ferruginated, and is often clearly separated 

 from the loose sand upon which it reposes. 



Cell Marl. — Above this rests the uppermost member of the 

 Cretaceous thus far discovered on the Western Shore of Mary- 

 land. It is mostly composed of dark greenish gray marl, and 

 narrow ferruginous strata imbedded in highly glauconitic sands 

 of coarse and variable texture. It is locally indurated in belts 

 of various widths ; and in its upper division is often closely set 

 with twisted, pocketed, or cell-shaped, laminar iron-stone, the 

 cavities of which are lilled with coarse, dry, grayish greensand, 

 holding white fragments of Terebratula harlani and Gryphaea 

 vesicularis. 



For convenience of distinction the name Cell Marl is here 

 applied to this member, since it does not precisely accord with 

 any named part of the Middle Marl Bed of New Jersey. It is 

 to be correlated with the " Shell Layer " of Prof. Cook, Geol. 

 N. J., 1868, p. 269, but it is much more heterogeneous in com- 

 position, and does not possess the stratum of fossil shells which 

 is so characteristic of it in Delaware and New Jersey. 



This upper division of the Cretaceous Marls forms a very 

 conspicuous unit of structure, which constitutes a large part of 

 the high hills from below Aisquith's Creek to the mouth of the 

 Severn river. In the deep cut above Winchester's Station it 

 rises to a height of 58 feet above the railroad, and thus reaches 

 an altitude of over 90 feet above tide. Below this point it is 

 profoundly eroded at irregular intervals, and forms the body of 

 a few abrupt single hills. Below the railroad bridge it mainly 

 slopes to a level of about 40 feet, and at length tapers oif to 

 about 20 feet above tide, where it terminates near the mouth 

 of the river. 



Eocene. — This basal member of the Cenozoic system of rocks 

 is well represented along a great part of the extent of the 

 section given in Plate A. Wherever it is accessible along this 

 register-line it rests on or immediately beneath the surface of 

 the country, and it is least disturbed and most developed in 

 those hill-tops which swell separately above the surrounding 

 level of the region. 



Here it is chiefly ferruginous in all of its phases. At base it 



