138 J. D. Dana—Geology of Vermont and Berkshire. 
carbonate has as yet been found only in Berkshire ; but its 
ready oxidation is a sufficient reason for its not being "exposed 
to view even where it is or has been a prominent source of the 
limonite, 
Most of the 2 saber in — preceding view with regard to the 
origin of the limonite have been recognized by different geolo- 
gists; and yet the view as a 5 whales is not so well understood that 
stated, with commendat atory remars by Prof. J. P. Lesle ey, "an 
nounced the conclusion, after a study of the iron ores of Nittany 
valley and other valleys in that State, that “the brown-hematite 
Sa eee. ore of the valleys belonged to the stratified limestone 
’ beds, and had been set free by chemical and mechanical decom 
sition” —ma king the iron to have existed originally in the lime- 
stone as the hydrated owide. 
Professor Hitchcock, in 1861, in the Vermont Geological Re- 
port, after stating that the limestone contained sometimes ten 
per cent of carbonate of iron, and referring to the iene UP of 
me cases from the quartz rock.” But to this mph a tag is 
added the ol error, hat é the iron had been taken “from the sub- 
aa rocks and re-deposited in connection with clay, pe and 
gra 
if this were the place for a full discussion of. the subje 
The change of the hard schists to soft clay is one of the 
most striking facts observed in the ore-beds. But if the iron 
was deriv pelo from pe carbonates, a powerful 
The different views of other authors might be here a 
A a 
* Historical sketch of Geological explorations in Pennsylvania other States. 
200 pp. 8yo. Harrisburg, 1876, p. 81. ns 
