368 
[Assembly 
Besides the above localities of the primary, we find it as before stat- 
ed, forming the base of the uplifts of the Noses, Little falls, and also 
Middleville. 
Great contrast exists between the layers of the primary masses and 
those of the transition class contiguous to them. The former present- 
ing disturbed appearance, exhibiting high grades of inclination, whilst 
those of the transition are like the deposits of tranquil waters, and to 
the eye often present an almost horizontal outline. From this differ- 
ence many important inferences follow, one of which only at this lime 
will be mentioned, namely, that the disturbance of the primary, was an- 
terior to the deposition of the transition class of the third district, and 
ishows the propriety of their separation. 
We have said that the layers of the transition rarely present other 
than an horizontal appearance, but when examined they show a two 
fold dip or inclination, one general in accordance with the contour of 
the primary nucleus, the other conforming to its more local changes 
or features. 
Specular and red ores of iron. These ores are to be referred to the 
period which intervened between the two classes of rock as they exist 
in the third district. That there are some members wanting to com- 
plete the series of that period is certain, from observations made out of 
the district, and in other counties which we shall advert to in our next 
report. To this period however we would state at present, that we 
should refer the Cambrian system of Prof. Sedgwick. 
Potsdam sandstone. This rock is well characterized in the northeast 
part of Lewis county, agreeing in all respects with the same rock in the 
2d district. South of that county it is not so, and therefore there are 
several varieties of it. Under this name, Ave include the layers below 
the calciferous sandrock" at the Paper mill on Spruce creek, and like- 
wise the layers below the same rock on East and West Canada creeks 
and at Amsterdam. In all these latter localities the structure of sand- 
stone is lost, and therefore in all respects unfitted for the purposes to 
which the northern sandstone is applied, namely, the lining of furnaces 
^nd for their hearth stones. For a full account of this rock, see Prof. 
Emmons' report for 1838. 
At Keeseville the Lingula abounds in this rock. As yet I 
have seen no fossil in it. 
