glazed and apparently very carbonaceous shales of the Hudsod — 
river valley, which have been so frequently mistaken for coal, 
as indicating a source from which, in those parts of the county 
where the true Carboniferous rocks are wanting, a supply of i 
as 
coal-measures themselves. These shales and slates seem to hav 
been accumulated under conditions somewhat resembling thos . 
which prevailed during the deposition of the Carboniferous? — 
ries, while the presence of so large a per-centage of carbon” 
them is rendered still more striking by the fact, that, ™ the 4 
Northwest, neither the rocks below, nor those above as far - 
the coal-measures, contain more than the merest trace of a 
mnaceous matter. From the base of the Potsdam to ‘the ee 7 
the Galena limestone, the whole amount of carbon present 32? e 
er hi a 
aps equalled twenty feet or more in thickness. A farth 
vestigation into the exact nature and distribution of the 
minous matter is contempla 
