1889] 



MARYLAND ACADEMY OF SCIENCES. 51 



lower down the creek. Proceeding up the small branch which 

 rises about a half mile back in the body of the high ridge, we 

 see a high knob of Cretaceous black marl, of very dense texture, 

 and almost as tough as cheese. This rises to a height of about 

 thirty feet above the bed of the stream, and at its outer end is 

 covered only by a thin deposit of such soil as has been washed 

 down from the higher part of the adjoining hill. But few fossil 

 shells have been extracted from this exposure, and they have 

 been hardly recognisable casts of Gyprimeria, Oueidlaea vul- 

 garis, and a few forms just like others that were extracted from 

 the cliiF lower down the creek, near Fort Washington. From 

 this bed, however, large numbers of coprolites, with some 

 sharks' teeth and amber, have been excavated by freshets in the 

 branch and carried down into the mud which lines the bottom 

 and sides of the drain. The other outcrops of the black marl 

 on this creek have thus far yielded nothing different from the 

 preceding beds, and do not present any peculiar features. They 

 are soon lost in the adjacent highlands, and cannot be reached 

 except by deep excavation of the overlying surface. 



As far as can be ascertained at the present time, the Cre- 

 taceous system of strata occupies an average width of about three 

 miles on the Western Shore. The undoubtedly continuous beds 

 vary somewhat in composition as they appear from one interval 

 to another along the line of strike, and differences in materials 

 may also be noticed in the ascending order of the beds. Thus, 

 near the inner boundary of the formation, above Collington, 

 the low dome-shaped beds are chiefly composed of coarse and 

 mixed greensand which becomes unevenly carbonaceous beneath. 

 Proceeding down the road to a short distance below Collington 

 the formation appears thicker, and the higher hills expose below 

 a bed of the more homogeneous black marl, overlaid by green- 

 sand of a somewhat loamy texture. Around Mullikin, on the 

 same road, very fine-grained, homogeneous, brighter greensand 

 makes up the dome-shaped hills, which are overlaid as usual 

 by a covering of coarse silicious, ferruginous sand and fine gravel. 

 The dense plastic black clay marl seems to be absent from this 

 region, but it appears at the base of Mount Misery on the 

 Severn ; likewise around the head of South river, and again in 



