SECTIONS IN THE BLACKWATER RIVER VALLEY. 149 



of it is covered by wash. The marked imeonformity between the Miocene 

 and Pleistocene is shown one quarter of a mile to the east of this bluff 

 where the Pleistocene extends to the water, the Miocene being cut out. The 

 bluffs are about the same height. In the second bluff the Miocene is 

 probably just below the water as the shells are washed out during storms 

 and thrown on the beach. 



SECTIONS IN THE BLACKWATER RIVER VALLEY. 



The St. Mary's formation is well developed in the valley of Blackwater 

 River where it contains extensive beds of shell marls which have been dug 

 in many places for fertilizing purposes. The shells occur in a matrix of blue 

 sand or sandy clay and are usually in a good state of preservation. Mulinia 

 congesta is especially abundant and in certain layers is practically the only 

 fossil present. Marl pits were visited one-quarter mile southwest of 

 McClelland, one-half mile northwest of Raynor, at Raynor, and 3 miles 

 northwest of Zuni. ISTumerous other abandoned pits occur in the same 

 region. 



[. Section left bank of Blackwater River at Old Seine Hole Landing, about 

 one and one-quarter miles north of Zuni {by water). 



Feet 



Pleistocene Sand, yellowisli 6 



Miocene. St. Mary's Bhie fossiliferous sand weathering to yellow, 



containing Crepidula acvleata var. costata, 

 Turritella variabilis, Area centenaria, Olycy- 

 meris subovata, Pecten clititonius, Phacoides 

 anodonta, Plicatula marginata 6 



Total 12 



II. Section of left bank of Blackwater River, about one-half mile north of 



Zuni. 



Feet 

 Pleistocene Yellowish sand 6 



Miocene. St. Mary's Y^ellow to blue sandy marl carrying abundant 



specimens of Mulinia congesta. .• 10 



Total 16 



At Zuni in an old well or pit near the pumping station bluish sand and 

 marl were exposed about 4 feet below the surface. Crucibulum grande. 

 Polynices heros, Turritella variabilis, Mulinia congesta and Panopea reflexa 

 are abundant forms present in the marl. 



