Volcanic regions

The whole mountain range that runs down from Canada to California has a long volcanic history.  Mt Shasta and the Shastina Crater looked most spectacular as we came down from Oregon.  Mt Shasta was active as recently as 200 years ago.

We were planning to visit the Lassen Volcanic National Park but found it closed due to the government shut down.  Nevertheless we captured a few nearby features.

Lava tubes are created when a hot lava flow cools and hardens on the outside and the inside then empties out leaving the hollow tube.  This entry point is where the roof has collapsed.  This tube was up to 6m wide and 3m high.

This is a large spatter cone 30m across and 20m deep.  Spatter cones are created when fountains of lava fragment in mid-air as gases escape.  The lava lands in showers around each vent, forming the cones.

This little lava tube drains a small spatter cone.  Intense heat caused the roof and sides of the tube to partially melt, forming icicle-like drips called 'lava cicles'.