REPORT 
OF THE 
SURVEY OF THE THIRD GEOLOGICAL DISTRICT. 
CHAPTER I. 
PRELIMINARY CONSIDERATIONS. 
The Third District is formed of fourteen counties and a half, as enumerated in the pre¬ 
ceding letter to Governor Seward. . It therefore comprises, as will be seen on reference to 
the map, all the area which exists between the Pennsylvania line on the south, and Lake 
Ontario and Jefferson county on the north, and a line extending north and south to the limits 
of the State through Cayuga lake at the west, and the counties of Delaware, Schoharie, 
Schenectady and Saratoga at the east. 
The rocks, or rather mineral products of the third district, belong to three systems, 
classes, or geological divisions. The first, or oldest to the Primary ; the second, to the period 
which intervenes between the Primary and the coal, well known by the name of Transition 
•class ; and the third, to the Quaternary, which includes the alluvial, commencing with the 
newer pliocene or upper part of the Tertiary, and extending upwards, embracing the most 
recent deposits of our globe. In the third district, the Secondary class, which commences 
with the coal, and the Tertiary class, with the exception of its upper part as just mentioned, 
as well as the Volcanic class, are entirely wanting. 
The rocks of the Primary class are in general readily known by their particles being crys¬ 
talline, from their containing no rolled stones, nor organic remains either animal or vegetable, 
nor do they show those well defined lines of division so common to the rocks of the succeed¬ 
ing classes of sedimentary origin. They are the most ancient of all the rocks, as their name 
signifies, which form that part of the crust of the earth which is known, and therefore form 
Geol. 3d Dist. 2 
