Thursday, July 26, 2007

July 2007 - Hat Creek and McCloud - Continued

Subway Cave

This cave, which is a lava tube, is in the Hat Creek area, near the town of Old Station, within the Lassen National Forest. Two thousand years ago, lava began spewing from deep cracks in the earth. The floor of Hat Creek Valley was covered by rivers of molten red hot rock. The top crust of lava cooled and hardened, the lava continued to flow in this insulated crust. Eventually the lava drained leaving tube-like caves.

The cave is 1,300 feet in length with zero visibility - flashlight needed!

Looking back at the entrance. Cave temp is 46 degrees F

Cave height 6-17 feet. Bud didn't hit his head once. Not always the case in previous cave adventures.
Devastated Area - Lassen Volcanic National Park
We were back in the park and took a short 1/2 mile trail through the Devastated Area. Two eruptions in May 1915 created this devastated area measuring 3 miles long and 1 mile wide. The first eruption created a snowmelt and mudflow that covered the region. The second eruption was "pyroclastic" where hot lava rocks flowed over the mudflow.

The huge rock on the left side of the picture was deposited here by the mudflow.

Did you know that some rocks are older than others?

The two on the left were formed 27,000 years ago when Lassen first erupted (gray and red dacite). The middle rock was formed during the May 1915 eruption and was carried here by an avalanche. The last two were formed during the May 1915 eruption as well (light dacite pumice and banded pumice) and were carried here by the ensuing mudflow and avalanche.

I bet most of you didn't even read that whole paragraph I painstakingly wrote! Anyhow, the real question is, how did they find these perfect specimens all lined up and ready for tourists! I'm betting the mudflow/avalanche weren't the last forces to move them.

Our girl dogs discovered boy dogs don't seem to care how long ago these rocks were formed, they must be marked!

1 comment:

Ali and Ross said...

I did too read the whole paragraph... I am NOT a skimmer! I think those rocks must have been used in some ancient ritual... what else would explain their positioning?

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