254 
fAsSEMBLY 
dense nature of the forest, and how short comparatively the period giv- 
en to the whole survey, the greatest economy of time becomes necessa- 
ry, for the realization of all its objects. 
In order to aid the reader, to avoid repetition, and to condense as 
much as should be done, so as to confine the report to a reasonable 
number of pages, more especially as Montgomery, Herkimer and Onei- 
da, have many rocks common to each other, a few brief matter of fact 
views of the general geology of these counties will be given. These 
views will tend to give method to the subject, and by pursuing the same 
plan in the subsequent annual reports, the whole will be connected to- 
gether; thus avoiding what otherwise would be dry and meagre detail, 
incident to a mere citation of geological products, and locality of the 
same. 
The series of rock which forms the third district, from the Pennsylva- 
nia line to the primary elevated region which separates the waters of the 
Hudson from those of the St. Lawrence, inclines at a small angle to the 
southwest, giving rise to that all-important practical consequence and 
fact, that every change of rock going north from the Pennsylvania line 
to the limits mentioned, brings us to a lower and an older rock; and 
on the contrary, every new or different rock we arrive at going south, 
carries us higher in the series, or nearer to the newest, the coal of Penn- 
sylvania, the final member of the great consecutive series of rocks of our 
portion of the North American continent. 
The different groups, or series, or formations, of the third district, 
have not all extended continuously over the limits mentioned, but ap- 
pear, like the coal of the State mentioned, to have been restricted in 
their progress north within certain limits, by a well defined east and 
west line. 
From the coal series to the Mohawk valley, the restriction or limit 
has been confined, so far as observations have been made, to a single 
series or group; but at the Mohawk valley, throughout Herkimer and 
Oneida, no less than five series terminate more or less abruptly, accord- 
ing to locality, giving rise to that great depression the Mohawk valley, 
or conversely, the high range or great elevation which in these two 
counties, and to the south of Montgomery, rises for a thousand or more 
ieet above the river. 
The valley of the Mohawk, therefore, forms in all that part which tra- 
verses the three above named counties, an all important geological line 
