Friday, September 28, 2012

Views of Lassen

Rock fall sign in front of Lassen Peak.
We're back again at Lassen Volcanic National Park, this time with a few quick views of Lassen Peak; photos were taken in early September. Hopefully the sign refers to rockfall from slopes and roadcuts, and not to a volcano falling apart or exploding in any way!

This view of the peak, taken from a pullout approaching the Lassen Peak traihead parking lot—and right across the street from a volcanic breccia locality—begins to show what's at least locally or colloquially called Vulcan's Eye. A nearby area about 2 miles southwest of the peak is called Vulcans Castle (the USGS doesn't use apostrophes—this thread explains why, linking to this USGS document, see Chapter 5).

Lassen Peak and Vulcan's Eye from close to the pullout at Lake Helen.
Vulcan's Eye
I couldn't resist taking this last shot of the peak from Lake Helen, which is a nicely photogenic high-altitude lake.

Tuesday, September 25, 2012

Fumarole at Sulphur Works

Old fumaroles at Sulphur Works
Here we are, back at Sulphur Works in Lassen Volcanic National Park, having walked across the road to view the current state of fumaroles (as of about 3 weeks ago. The shadowed, small holes above the large indented or concave area, approaching the top of the triangular upper face is where numerous fumaroles have been active during many of our previous visits to the area (visits by MOH and I, only one visit on this blog, with photos from October, 2006).

couple videos on YouTube (2007, 2010) show the old vent steaming away, and the first one shows just how pockmarked that little hill was with fumaroles!

Active fumarole surrounded by large orange circle
Now we've moved down the road from the viewing area, to get a clearer view of the fumarolic vent that was steaming, that pock-mark in the center of the large orange circle. I suspect the circle may be formed not only by iron oxides, but possibly some jarosite, a sulfate mineral, and some native sulfur.

Close up of the active fumarole
Here we've zoomed in on the active fumarole, a small hole in the ground emanating steam that is no doubt adding to the pervasive, sulfurous stink of rotten eggs.

My video of the active fumarole
One interesting thing about the location of Sulphur Works, including this fumarole and the boiling mud pot across the road: Sulphur Works is near the center of ancient Mount Tehama (or Brokeoff Volcano, as it is sometimes known), a large stratovolcano that was active between about 600,000 and 400,000 years ago.

More Reading:

“Hot Water” in Lassen Volcanic National Park—Fumaroles, Steaming Ground, and Boiling Mudpots - U.S. Geological Survey

Explore the Hydrothermal Areas - Lassen Volcanic National Park

Tuesday, September 18, 2012

Mud Pot at Sulphur Works

Boiling mud pot at Sulphur Works.
This post is mostly just an opportunity to put up a few quick pictures (and video) from a recent trip to Lassen Volcanic National Park, which MOH and I took a couple weeks ago when I had an extra day off. (Yay for days off!)

It was a clear day, and we drove into the park from the south, taking Highway 36 to Highway 89 north (AKA the Main Park Road), up past the newish Kohm Yah-mah-nee Visitor Center, past Emerald Lake, past the turnoff to Bumpass Hell, past Lake Helen, past the Lassen Peak trailhead, and over the pass a little ways until we turned back around (map of the park).

We had stopped at Sulphur Works on the way up to note the ways in which the hydrothermal activity had changed since our first official visit to the park sometime in the early 2000s. (Earlier visits of mine/ours prior to this more recent era have faded into a distant non-digital past.)
As far as I know, this boiling mud pot came into existence in late 2007, and it grew considerably by early 2008. We remember from earlier trips that the main roadside attraction (besides a side trail that is now closed due to a shifting in the location of hydrothermal features) had been across the road: an active fumarolic area with several vents, and possibly with a mud pot. These fumaroles were barely steaming on our recent trip, though fumarolic activity can vary with air temperature and other factors.

My somewhat shaky mud pot video.

If anyone knows anything more definitive about the history of this mudpot, please let me know.

UPDATE 21Oct2012: Google Street View shows several fumaroles but no mud pot in this location in photos dated 2007.

Wednesday, September 12, 2012

When the Road Turns to Bug Dust

When the road turns to bug dust... keep on hiking.
Lizard on far rock for scale.
"Bug dust" is apparently a Nevada term for the loose silt and clay that develops when a soil is overworked by tilling or any other means. I've mostly heard the term in reference to the billowing powder dust that develops on some dirt roads — two track and otherwise. The dust can become so thick that it will clog your air filter and stop your truck.

This particular bug dust isn't that thick; it was created mostly by ATV's during a fairly short period of time.
Closeup of lizard.
Walking through the nasty stuff.
A closer closeup.
Truly silted and bug-dusty roads would be quite unpleasant to walk through, as the fine powder can reach several inches or more thick. Our new hiking spot, so far not featured on the blog except for this dusty post, is along an old two track road that was closed to motorized traffic in spring and early summer, so the dust, so far, hasn't gotten as bad as it could. It will probably never reach the epic bug-dust category claimed by many basin and alluvial fan roads in Nevada. Those roads are essentially impassable with windows down and call for vehicle cabins that are pressurized by recirculated air.

On our most recent hike up that same canyon, we took a side road not frequented by many, thus avoiding most of the bug dust.

Monday, September 10, 2012

Rock Color Links

Here are a few links I find useful in comparing RGB, HEX, and UCL or Munsell colors, though these don't all match the original Rock Color Chart, which is no longer available. The new Rock Color Chart colors do not match the old chart completely, and is organized in a way that I find difficult for real world use.

Geological ROCK-COLOR CHART - online pdf version (new)

The original - no longer available, though QCQA says, "Discontinued...Check with us later," and "Usually ships within 24 hours" — NOT.

RGB Chart & Multi Tool: HEX, RGB, Munsell.
Universal Color Language, Level 3: Munsell and HEX.
NBS/ISCC Color System: Munsell and HEX

Color Theory: Completed Munsell Color Charts - Gnomicon blog - 5R page. This site is *still* down (permanently?), and my notes don't tell me what it was.

More About Colors:
Color-Name Dictionaries

Robert Krimen > Color-Library

The Michel-Lévy Interference Color Chart - although the colors look a little washed out

Wednesday, September 5, 2012

Icky with Anorthosite

Besides the obvious greenish feldspar, the countertop rock is composed of black pyroxene, gray metallic minerals (magnetite or ilmenite are likely, but I didn't bring my magnet, magnetometer, or portable xrf), and pyrite.

Also see:
Geo-beers: Gimme an Icky

Anorthosite and labradorescence

Theme and Variations on Anorthosite and Labradorescence

Rock 366 : Day 72 : Anorthosite with sulphides

Labradorite at Wikipedia (photo)