346 J.D, Dana on the Volcanoes of the Moon. 
dence in the area around, as has happened at Kilauea. The same 
- facts are shown by the mountains Abulfeda and Timocharis ; and 
we have already remarked that the crater of the last mentioned 
has very nearly the features of the Kilauea pit. Again they 
might finally so far diminish their size by the cooling in progress, 
that there would no longer be free ebullition, and the vapors 
having to force their way up, would break through with explo- 
sive violence, producing an alternation it may be of cinder and 
lava eruptions, or cinder eruptions alone at summit, and raising 
up conical pointed peaks. These different phases, itroorhieotion 
with fissure eruptions and upliftings from contraction, from both 
_ which causes ridges might result, give us a complete and com- 
prehensive view of the origin of the moon’s features. 
Are the lunar craters still active? To avery great extent ie 
surface has evidently cooled, and whether there are any active 
points is a matter of doubt. But without admitting igneous ac- 
tion at the present time in some parts, how can the facts men- 
tioned with regard to the difference in the light of different por- 
tions of the moon’s surface (p. 341) be satisfactorily explained ? 
This difference may possibly be partly accounted for on the 
ground, (borne out by Kilauea,) that the bottom of a crater may 
have a smoother surface than the-declivities or plains exterior. 
Perhaps also there is something attributable to a difference of ma- 
terial, though this is not probable. If these explanations are 
received as sufficient for the craters, they fail of satisfying us 
with regard to the light streaks which are so remarkable about 
some cones—coursing over ridges and depressions without inter- 
ruption. The fact of illuminated walls to a crater when the bot- 
tom is not illuminated, and the general diffusion of light when 
one or more bright areas of small extent may be distinguishet 
are also points not easily understood on the above suppositions- 
May it not be, that we should attribute some of the instances of 
lighted areas to a covering of vapors from the igneous action be- 
neath? The light streaks are not depressions, and therefore not 
broad fissures having the great width they exhibit ;. but they 
may be regions containing many fissures from which vapors are 
escaping, and by the coalescence of such areas, the summit of @ 
rater like Euler might appear illuminated. Such vapors might 
80. cover the bottom of a crater that the walls would pone 
ite: — might pesca terre famear a crater 
rE 
