Sunday, June 13, 2010

Mega road trip - Day 12

Today didn't work out quite as planned.  The idea was to drive from Susanville, CA up through the Lassen National Forest and over to Lava Beds National Monument north of Mount Shasta on Forest Service Road 49.  Problem was, after driving 30 miles up Forest Service Road 49, we discovered it was blocked by snow (a sign at the start of the road would have been nice).

We did, however, visit a few lava beds in the area (erupted within the last few thousand years) and even went through a nice 1,200 foot lava tube called Subway Cave.  Lava tubes are commonly formed in lava flows when a crust forms above a flowing river of magma just beneatht the surface.

It's also common for lava tube ceilings to collapse.

Since we couldn't get to Lava Beds National Monument without a very long detour, we decided to drive around Mount Shasta instead since we kept seeing peeks of it through the trees as we drove around in the area.

Mount Shasta in Northern California is the second-largest volcano in the Cascades Range (only Mount Rainier in Washington is larger).  The Cascades is a range of volcanic peaks running from northern California up into British Columbia, Canada and formed by the subduction of the Juan de Fuca plate of seafloor crust under the North American continental crust.

As the plate subducts, it causes periodic earthquakes and, when it reaches a deep-enough depth, begins to melt to provide magma for volcano formation.  Some of the older folk reading this may remember the Mount St Helens eruption of May 18, 1980 in this range.

Mount Shasta has erupted every 600-800 years on average and last erupted in 1786.  It's interesting to drive through the many towns around the base of Shasta and wonder how they will fare when (not if) Shasta erupts again.  The Cascades volcanoes are not extinct, the subduction of the Juan de Fuca Plate is still generating magma - but rather dormant or sleeping until enough magma is generated to fuel an eruption.

We did find a highway from the town of Shasta that led up to around 7,000 feet before the road was closed due to snow.  That's about half-way up the 14,179 foot peak.  Here's the view of the peak from the road.

The end of the road was quite busy when we arrived on this Saturday afternoon.  There were dozens of climbers around who had presumably returned from summitting (or attempting to summit).  There was also a CHP helicopter taking off and about 10 official vehicles (Sherrif, Forest Service, and Search & Rescue) since a pair of climbers was hurt on the mountain and had to be medivaced off.  A common occurrence from what I've read since the mountain is so accessible and some of the people attempting to climb it shouldn't.

A final view from the north of this spectacular mountain.

From Shasta we worked our way up I-5 to Grants Pass, OR where we're spending the night.  Tomorrow is the Pacific Ocean and Highway 101.

No comments:

Post a Comment