Page:Popular Science Monthly Volume 29.djvu/397

Rh him to endeavor to ascertain their origin during his voyage to Northern Greenland in 1870. After much searching, with the aid of what directions the natives could give him, he at last found the object of his investigations in the hill of Blaafjeld, or Ovifak, near Disco Island. Blocks of iron were lying on the shore at the foot of a high cliff composed of basalt and conglomerates of the same rock in alternation; and more than twenty masses, containing not less than twenty-one thousand kilogrammes of metallic iron, were collected within a small space. They were at first supposed to be of meteoric origin, because they contained nickel, and exhibited figures which had been regarded as peculiar to meteoric iron. But this view was proved to be incorrect when M. Steenstrup, under a commission from the Danish Government to investigate the conditions under which the iron occurred, found, at one point on the coast, native iron actually imbedded in the basaltic rocks, the appearance of the larger grains of which was precisely similar to that of the scattered blocks previously found. The presence, in the eruptive rocks of the earth, of iron alloyed with nickel, similar to meteoric iron, and having the crystalline texture which had previously appeared to be an exclusive characteristic of the latter, has therefore become incontestable. It is proper to add that the metal in this condition is not a fortuitous and isolated accident in Greenland, but that it is found in many places and over considerable districts.

The geological structure of the northern part of that country is especially distinguished by the development of eruptive rocks of a relatively very recent age. It is one of the largest masses of basalt with which we are acquainted. It begins at the sixty-ninth degree of latitude, and disappears near the seventy-sixth degree, under the vast continental glacier which prevents all further exploration of the surface. It is reasonable to suppose that the eruptions of which these rocks are the result brought up metallic iron, of which they seem to indicate the existence of large masses in the deep interior. This fact has also to be taken account of in the theory of terrestrial magnetism.

After having sketched, twenty years ago, the numerous features of resemblance between the meteorites and the deep terrestrial rocks, and having shown how some of them can be imitated by a partial deoxidation of those rocks, I added: "There is nothing to prove that beneath those aluminiferous masses which have furnished, in Iceland, for example, lavas analogous to the meteorites of Juvinas, that beneath our peridotic rocks which the meteorite of Chassigny closely resembles, there may not be found masses in which native iron begins to appear, or resembling meteorites of the common type; then, below these, types richer and richer in iron, of which the meteorites offer a series of increasing density, from those in which iron represents nearly half the weight of the rock to massive iron." Five years after these lines were written, the great masses of native iron alloyed with nickel,