MARYLAND GEOLOGICAL SUKVEY 105 



the form of a cauliflower. These mark the boundary between the Beek- 

 mantown and Stones River limestones. As explained on another page, 

 the secondary silicification necessary to form the cauliflower variety is 

 supposed to have occurred in the time interval between the two formations 

 when the Beekmantown rocks formed a land area. 



Sometimes the upper Beekmantown strata holding the Turritoma 

 fauna do not weather as described above, but show the usual occurrence of 

 smooth, rounded outcrops in which the fossils, although numerous, appear 

 only as natural sections in the rock. Such exposures along the National 

 Highway in the vicinity of Huyett, Maryland, have yielded the following 

 species : 



Fossils of the Turritoma Zone in Maryland 



Dalmanella electro, (Billings) 

 Pleurotomaria ?? gregaria, Billings 

 Hormotoma gracilens (Whitfield) 

 Turritoma acrea (Billings) 

 Maclurites oceanus (Billings) 

 Eccyliopterus disjunctus .(Billings) 

 Cyrtocerina mercurius Billings 

 Trocholites internistriatus (Whitfield) 

 Isochilina seelyi (Whitfield) 



Traces of this fauna, although always in poor preservation, have been 

 noted at numerous places in Maryland, in fact Beekmantown strata 

 exposed near the boundary line of the Stones Eiver areas usually reveal 

 one or more layers showing natural sections of these fossils. 



TOPOGRAPHY AXD RESIDUAL PRODUCTS. The Beekmantown as a whole 

 produces gently rolling country, but the lower Stonehenge member and 

 a zone about 800 feet above the base of the formation give rise to very 

 characteristic topographic features, which are of extreme importance ill 

 the mapping of areas in which rock outcrops are infrequent. 



These topographic features are the result of the various siliceous 

 products left in the soil by weathering of the limestone. They are so 

 distinctive that they become as important factors in the identification 

 of the strata as the .characters of the rock itself or of its contained 

 fossils. In the absence of fossil remains or indeed of satisfactory rock 



