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) 
g Asaphus platycephalus Stokes (a) 
10 Calymmene callicephala Green (r) 
II 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 Hoffman ferry, 
known as Wolf's 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 
