240 Prof. Silliman’s Address before the 
_—fifty or sixty feet—has been discovered, im s#tu, near Abingdon 
in Virginia, along with gypsum shale, and probably sandstone. 
There are abundant salt fountains at the same place, and the 
mineral salt was discovered in boring for salt water. 
This is an interesting feature, added to our geology. We had 
before vast numbers of salt springs, but no solid mineral salt short 
of the Rocky Mountains. There, in a mountain on the Sal- 
mon River, it was observed some years ago, by the Rev. Mr. 
Parker, a missionary, who reports it to be floored and roofed by 
sandstone. (This Jour. Vol. xxi, p. 214.) 
The tin ore, (oxide.of tin,) reported last year, as discovered 
by Dr. Jackson in the White Mountains, has been found by him 
in increasing quantity, and small bars or ingots of the metal have 
been extracted by the discoverer. This is an important addition 
to our metallic resources; and the extraction of metallic zine 
from blende (the sulphuret) by Dr. Jackson, from the ore found 
at Eaton, New Hampshire, agreeably to the practice now adopted 
in Germany, is a happy beginning upon an ore heretofore re- 
garded as of little value, but existing in great quantities in the 
United States. _ 
We forbear to dilate upon the simplicity and immensity of 
many of our geological formations—a vast country constructed 
upon one great model, with such unity of design and with such 
persistence in the plan, that particular formations are found as- 
sociated and running longitudinally northerly and southerly, 
through the entire continent. 
The best architectural materials, granites, traps, porphyries, 
Sienites, serpentines, soapstones, limestones, primary slates, and 
slaty rocks of every geological age, sandstones and conglomerates, 
abound. The most useful minerals are found also in large quan- 
tity—ores of iron, copper and lead, gold and silver, the latter 
especially as it exists in argentiferous galenas. Above all, coal- 
fields of unequalled magnitude, thickness, extent, and richness, 
with clays, marls, and sands, and soils, of every variety, furnish 
to-our population all the means of national wealth and individual 
fosperity. Over vast regions, there has been no serious distur- 
bance of the strata; they have been gently lifted from the waves, 
en without a fracture, dislocation, or an intrusion of an igneous 
tock, for hu i This geological quietude affords 
vast advantage in working our coal-fields, especially the trans- 
