Lava flow trail
side trip:
Take a closer look
at a monster vesicle |
 |
| The
surface of this vesicle has broken so that you can see through to
the other side. |
 Walk just around the corner from stop 1 and you'll see a really
huge vesicle! While lava is still very hot and fluid, gas bubbles form
and work their way toward the lava surface. If you look at an active lava
flow you can watch bubbles rise to the surface, then POP! with a spray
of molten droplets as gas escapes from the flow.
Often the surface of the lava flow cools and hardens first, forming
a crust with still-flowing lava beneath it. In this case, gas rises but
is trapped beneath the crusty roof. As more and more bubbles are trapped
by the roof, they grow together to form a really big bubble like the one
you see here. |
|
Compare
this mega-vesicle at Sunset Crater with the one forming just beneath
the roof of this lava tube in Hawaii. Even though the lava has long-since
hardened at Sunset Crater, you can easily see that the processes forming
these two bubbles are very similar.
Step
up to take a closer look at the roofs in these photos you'll see
something that looks like stalactites found in limestone caves. These
solidifies lava drips provide another reminder that the trail you are
walking on was once a 1000°C-plus molten lava flow.
| |
 |
| Mega-vesicle seen from the Lava Flow trail. |
This
image shows the thin, crusty roof above a lava tube. Click
here to view Pu`u`O`o, an active cinder cone.
| |
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