LOWER SILURIAN SYSTEM OF EASTERN MONTGOMERY CO. 43]I 
man station. South of the Mohawk the Calciferous sandstone 
appears in low ledges along the greater part of its outcrop. The 
Trenton limestone produces a gentle topography with scarcely any 
ledges or sharp lines. | 
The second region, that of the Utica shale, is characterized by 
rounded hills rising at their maximum to an altitude of 1062 feet 
A.T. or about 800 feet above the Mohawk river. Here again there 
are no deep glens. The formation is very homogeneous, there 
being few hard layers to form waterfalls or steep slopes by the 
more rapid disintegration of underlying shale. The highest parts 
of this region are near the parting of the Utica and Hudson river 
shales. After the removal of the latter formation the Utica shales 
are rapidly reduced to base level. 
The third region, that of the Hudson river formation, furnishes 
by far the most interesting topography, being characterized by bold 
relief; the very soft shales interstratified with firm layers of sand- 
stone produce an abundance of deep and very narrow glens and 
steep hillsides. Waterstreet hill back of Rotterdam Junction rises 
to an altitude of 1400 feet A.T., nearly 1000 feet above the level 
of the Mohawk river. Its northern slope is steep and with the 
southern slope of the Glenville hills across the river forms the 
Notch, so conspicuous a feature of the northwestern horizon from 
the vicinity of Schenectady 10 miles to the east. Eastward the hill 
plunges abruptly to the bed of the Plotterkill, forming one of the 
finest glens in the eastern part of the state. The streams empty- 
ing into the Mohawk in Rotterdam township form a series of beauti- 
ful and characteristic waterfalls. Almost every heavy sandstone 
layer has its fall. Normankill in the southern part of this region 
flows for the greater part of its course in a deep narrow valley 
often amounting to a gorge with precipitous sides. This stream, 
it will be noted, empties into the Hudson river near Albany. The 
divide between the Mohawk and Normankill drainage reaches an 
altitude of over 1400 feet A.T. and extends with little variations 
from this amount through Rotterdam, Princetown and Duanes- 
burg townships. It will be seen that Mariaville pond and Feather- 
stonaugh lake are situated only 100 feet below the summit of the 
divide which is less than half a mile south of the latter. 
The hills of these Hudson river strata rise abruptly along the 
Hudson-Utica parting. The valley of South Chuctanunda rapidly 
