and Volcanic Substances. 229 
masses, sometimes breaking through the hardest rocks in 
jets, and forming peaked hills and knobs—sometimes for- 
cing up the stratum from below; as at Antraigues in Au- 
vergne, which is built on curved basalt that supports enor- 
mous masses of eres ie titi 16. metimes in 
Dykes reaching to gre nees and of unknown depths, 
cisnopting and tna a strata through which the dyke 
violently brok "he ays coal Dyke of the. 
ot England of this kod extends from sea to sea. (White- 
hurst-Bakewell.) These Dykes burn, char, ie. or indu- 
rate all contiguous substances, and break pls and dislo- 
cate all metallic veins, as we bave already se 
egetable organic remains (Humbold,) aad animal also, 
(Brugnatelli, Dr. Richards son,) have occasionally, though 
rarely been found in Basalt, adhering | to, or enveloped 3 in 
it: so has charred wood. 
hese organic remains are not found in the prismatic or 
figurate, and only io the aes Basalt, which has met with 
them in its course. I havea shell imbedded i in the fused 
slag of an iron furnace. Metallic substances, excepting 
iron, and titaniferous 1 ce are rarely found in Basalt. 
Columnar basalt has been found with water in its cells : 
perhaps owing to steam, that not escaping, has cooled into 
err meena s Geognosy, 1808, p. 186, and 3 Sou- 
vie 
Base bak hills are much subject to rents and fissures; and 
are often found with fragments of al] shapes and sizes at 
the. and sides; assuming a breccious structure ; and 
cemented to the aubjacent rock as at La Spisso, Reconro, 
. Ferber Tray 
Basalts are frequently found coverings passing into, and 
which Werner 
calls Wacke, Grunstein and Porphyritic sie abst, so that it is 
me oy? ans to mark the line of distinction between 
Hi......No. 4 
eeeene 
