and Volcanic Substances. 938 
3 Lavas. | The Floetz-trap Formation. 
They pierce through and beara-| So does floetz trap basalt. 
way before them all rocks indiscrimi- 
nately of whatever description. 
They cover indiscriminately all! So does floetz trap. 
rocks in their way. 
They rarely contain or envelope,| Such isthe case with floctz trap. 
vegetable, animal, or metallic sub- 
stances save titaniferous iron. 
They charr contiguous coal\; they} So does flostz trap. 
burn all the rocks in contact with 
them. 
They are not associated with any| Such is the case with ficetz trap. 
rocks or any veins in particular. 
They are unconformable to the} Such also are the fleetz trap. 
rocks on which they are poured, un- 
less while in a state of great fluidity. 
They form columnar masses when| 
slowly cooled. 
These columnar masses, impossible] No other way remains to account 
to be distinguished in any way from| for the forms of figurate basalt of floetz 
the columnar basalt of floetz trap, are! trap. 
surely and undisputedly attributed 
to cooling after ignition. 
They have been found abounding| The same isthe case with floetz trap 
in countries where craters have been| basalt. 
traced but recently. 
There is no possible mode ofcon-; The same difficulty occurs as 
jecturing from known fact how aj fletz trap basalt. 
Lava basalt can be dissolved in wa- 
ter: and we know they haye been 
fused by fire. 
It is absolutely impossible to sup-| It is equally impossible to account 
pose amass of Lava, in a soft state| for Whin-Dykes, where the same ap- 
from aqueous solution or dispersion, to! pearances exactly take place. 
force its way, upwards through the 
whole range of superincumbent stra- 
tato the surface. Yet we know this 
is done. 
Wherever we can observe this ef-| We are boundin the case of Whin- 
fect from Lava, in our own time, or| Dykes of floctz trap, to account for 
know it from historical record, it has} similar effects from the operation of 
been caused by igneous, fusion, not) similar causes. 
by aqueous solution or suspension. 
None of the appearances or effects} | Nor will those of floetz trap basalt, 
of basaltic Lava, will admit of ex-! and Whin, or Dykes of toad-stone or 
planation from the agency ofsolution| Amygdaloid. ‘The difficulty is equal 
or diffusion in water. on both sides. 
What then are the arguments used by those who. oppose 
the igneous origin of the newest fleetz trap? 
It is said, 
(a) They overlie and alternate with the secondary and 
alluvial formations, and therefore belong to them. 
So does the floetz trap. 
