Note 4 — Chapter XV

This structure in frozen snow was long since observed by Scoresby in the icebergs near Spitzbergen, and, lately, with more care, by Colonel Jackson (Journ. of Geograph. Soc. vol. v, p. 12) on the Neva. Mr. Lyell (Principles, vol. iv, p. 360 has compared the fissures, by which the columnar structure seems to be determined, to the joints that traverse nearly all rocks, but which are best seen in the non-stratified masses. I may observe that in the case of the frozen snow the columnar structure must be owing to a “metamorphic” action, and not to a process during deposition.