are ae Ss ee 
J. L. Campbell—Dufrenite from Rockbridge County, Va. 65 
of the relation of the two ety wale of Florida and Yucatan 
to the Gulf Stream on the one hand, and the basin of the Gulf 
on the other. The eastern akon of “boat fall off steeply into 
eep water, while the gulfward shores are bordered by the 
shelf, 100 to 130 miles in width, which breaks off into deep 
water at Aye 100-fathom line. It would thus seem a priori 
probable, that both peninsulas were elevated at the same time 
to a somewhat similar extent as regards their lowlands; 
and if so, this event cannot but have exerted a considerable 
influence upon the climate of the regions concerned, as well as 
upon the nature of the Gulf-border depo sits. 
Cannot something be done toward a prompt solution of this 
interesting problem in American Geology, upon which depend 
so many other mooted questions of first importance? A single 
season’s yachting excursion along the shores of Mexico would, 
under the hands of a well-posted observer, be amply sufficient 
to settle all the main points. Even a few specimens of rock 
from prominent points might go we toward the elucidation. 
But any such exploration should be made,-not with a view to 
the discovery and naming of new cious but with that of 
working from the base-line of the well-observed facts and 
in order to accomplish this end, the weary catalogue of spuri- 
ous species that now encumber our lists of Tertiary shells, 
must be thoroughly revised from the present biological point 
of view, is pemergy true. Nowhere would a richer field 
reward the labors of the faithful worker. The time for this 
has certainly come—but where is the man: 
Arr. XIIL—On iibes from pie County, Va.; by 
L. Camps 
Dvurine the summer of 1875, a number of specimens of iron 
ores from the Blue Ridge range in Rockbridge County, Va., 
were brought to my office for examination. One of these at 
once arrested my attention by its peculiar structure, color and 
luster, It had been taken from the mine in which it occurs 
partly in the form of irregular nodules, and partly as incrusta- 
tions on the surface of an underlying bed of limonite. 
broken open, the newly exposed surface showed a radiated, 
coarsely fibrous structure, with a Poit dull silky luster, and a 
dark greenish brown (almost black) color. Where the surfaces 
Am. Jour. Sct. ies Serizs, Vou. XXII, No. 127.—Juty, 1881. 
