LOWER SILURIAN SYSTEM OF EASTERN MONTGOMERY CO. 449 



numbers of Trinucleus concentricus Eaton. The fol- 

 lowing species were obtained in about an hour's search (2F) : 



1 Escharapora recta Hall (r) 



2 Monticulipora (Prasopora) lycoperdon Say (r) 



3 Lingula quadrata Eichwald (r) 



4 Orthis (Dalmanella) testudinaria Dal. (a) 



5 Rafinesquina alternata (Con.) Hall and Clarke (c) 



6 Plectambonites sericea (Sowerby) Hall (c) 



7 Rhynchotrema capax (Con.) Hall and Clarke (r) 



8 Trinucleus concentricus Eaton (aa) 



9 Asaphus platycephalus Stokes (a) 



10 Calymmene callicephala Green (r) 



11 Stictopora elegantula Hall? (r) 



12 Crinoid segments (r) 



Similar layers are exposed at several points along the fault scarp 

 toward Hoffman ferry but in general no accurate section can be 

 measured on account of the derangement of the rocks produced 

 by the fault which will now be described. 



Hoffman ferry fault. By referring to the accompanying geologic 

 map it will be seen that the group of limestones on which the city 

 of Amsterdam is placed is abruptly sheared off along a line running 

 nearly straight from the western central part of Charlton township 

 to a point about one mile southwest of Pattersonville. From these 

 points the line curves westward in its southern extension and is lost 

 in the western declivity of Princetown hill. Northward it gives off 

 several branch faults and has been traced by the early geologists of 

 the New York survery and more recently by Mr Darton and 

 Prof. Prosser to the Archaean mass northwest of Saratoga. The 

 most interesting part however both from the standpoint of geology 

 and of topography is at the deep glen north of Hoflfman ferry, 

 known as Wolfs hollow, where there is an escarpment on the 

 western side of the glen forming a mural cliff of over 100 feet in 

 places almost perpendicular. The glen has been cut presumably 

 by the creek which may now be seen as a diminutive stream flow- 

 ing by the roadside through the glen, where the soft shales of 

 the Utica(?) and Hudson river formations lie inclined at a high 

 angle against the hard resisting wall of Calciferous sandrock. One 

 may see therefore on the one hand a wall of massive calcareous 



