858 N. H. Winchell—Dall’s Observations on Arctic Ice. 
and second, that these drifts are largely the debris of half- 
decomposed feldspathic gneisses and schists, of which the feld- 
spathic particles are undergoing kaolinization, liberating the 
alkaline salts, while the silica attacks such fragments of organic 
matter as happen to be present, subjecting whole trunks of 
trees of more than a foot in diameter, to complete silicification 
even while lying within a few feet of the surface, and facing 
the drusy rifts of the wood with perfectly terminated quartz 
crystals, 
Raleigh, N. C., March 15, 1881. 
Art. XLV.—Dall’s Observations on Arctic Ice, and the bearing 
of the facts on Glacial phenomena in Minnesota; by N. H. 
WINCHELL. 
* This Journal, xx, p. 335 and xxi, p. 104. 
