THIRD ANNUAL REPORT 
Of the Geological Survey of the Third District, by 
Lardner Vanuxem. 
Montgomery, Herkimer, Oneida and Oswego, were the counties 
which formed the subject of the last report. It was in consequence of 
those counties presenting but few of the attractive valuable mineral pro- 
ducts, those which do not enter into the composition or form rock mas- 
ses, but are the associates of certain rock masses, that it was thought 
better to adopt a more general plan than the one contemplated at the 
commencement of the survey. 
With few exceptions, all the mineral wealth of the Third District 
form portions of the great series of rock or geological masses, the right 
understanding of which requires that the position which each kind holds 
in the series, should be known. The same reasoning applies to those 
mineral substances which do not enter into the composition of the series, 
from making but a small part thereof, but have a determinate place 
therein; and the same likewise may be said of those products derived 
from certain materials of the series, and hold a position extraneous to 
them. Such are calcareous tufa, lake marl, bog-iron, and we may in- 
clude the products of alluvium likewise. 
This blending of the two methods in the annual reports, greatly fa- 
cilitates the Geologist of each district in the collecting of materials for 
his final report, being aided not only by his own eyes, but the eyes of 
his co-associates. For these and other reasons, we shall continue the 
same plan in the present report. 
It cannot be said that any of the counties have been finished or tho- 
roughly examined, for it often happens from the materials which form 
rocks, having been furnished from different and often opposing geogra- 
phical points, that a rock which is well developed or forms a thick 
[Assem. No. 275.J 31 
