First Creek Jasper

Jasper, First Creek

There is a well-known location for agate and geodes in First Creek canyon, on the Blewitt Pass highway north of Ellensburg.  (see:  http://happyrockhound.blogspot.com/2011/05/first-creek.html)  I have passed by there several times on my way other places, but have never really explored the upper parts of the watershed. However, earlier this year, I did poke around the lower creek a bit, on the assumption that rocks wash downhill...

One of my finds was a weathered brownish lump that revealed just a hint of patterning inside. On a hunch, I tossed it in the bag and brought it home for the polisher.  This is what it looks like now,  after the final polish, a rather graceful stone of brown, orange and a streak of blue-gray. In other words, quite unlike anything I have ever seen come out of First Creek.

Maybe it's a glacial remnant from somewhere else, or part of a filled cavity somewhere in the local basalt. Either way, it's my "rock of the day."

Poppies Transformed

A few months ago, a reader was kind enough to share with me his location for Olympic Poppy Jasper. He  generously took time out of his day not only to lead me to the outcrop, and but to help search for specimens on my behalf. I came home with a boxload  of rough - and only now have started polishing it.  This two-inch piece is small, but with a brilliant color, and striking, naturalistic shape. Needless to say, I'm thrilled.
To be honest, none of the material looked that impressive when I got it home. These scarlet poppies do not normally form massive  blocks: most of what we found were modest little clusters in otherwise rather uninteresting basalt. But trimmed and tumbled, they really pop.
But the best thing about the day was the unselfish attitude of my host. I will remember that every time I look at these handsome stones.

Geology 101 Redux

Variolite "Cross-section" - Elwha River

One of my favorite finds from my search for variolites on Sunday was this fellow. About 6" inches long, it shows the distinctive feldspar "dots" of all variolites, but grading dramatically in size from the bottom to the top.  Varioites are believed to form inside "pillow lavas" or basaltic lava that erupts underwater, forming unmistakable round structures visible in many NW roadcuts (especially on the Olympic peninsula). My sources tell me that the smaller dots form as the edges of the pillows, which cool more quickly, while the larger dots grow in the slower-cooled, better-insulated interior of the rock.

This makes sense to me, but whatever the explanation, I thought this sample was particularly cool...

Return of the River

Variolites,  Elwha River

One of the biggest things happening in the Northwest this year has been the beginning of two dam removals from the Elwha River on the Olympic Peninsula. It is a huge project, the largest dam removal effort ever undertaken in the US and promises to restore both a spectacular river and the salmon runs that used to inhabit it.  For more information on the project, see here.

I had a chance to visit a part of the river yesterday that has re-emerged from the lake that once covered it;  gravel bars have appeared that I have never seen before!  And those gravels were covered with a rock that I have been tracking for years - Variolites (see previous posts here). I have been convinced that one major source for this rock is in the Elwha Valley. Now after finding dozens within a small area, I am convinced of it. I guess the trick will be to travel upstream until I can't find them anymore - and then look in between!

These things have no gem value, or any other reason for being sought, other than personal obsession. Stay tuned.

Mystery Solved... "Variolites"

Variolite cobble, Crescent Formation, Olympic Peninsula WA

For several years I have puzzled over the origin of this stone type, which is a remarkably common component of beach gravels around the Olympic Peninsula. (See my earlier post of July 19) It is so common, in fact, that it argues for a local source.  I haven't found that source yet - but I think I have discovered what it is.
The answer came from Scott Babcock, Professor of Geology at Western Washington State University, who has studied the Crescent Formation extensively.  He proposed that they were something called a "variolite" said to be a metamorphosed basalt (possibly pillow lava).  He sent me Googling for the quite-famous (though not to me) variolites of Durance, France.  Bingo.
A quick look at some photos of the Durance rocks was all I needed - these are clearly related.  (And there is a LOT of  basalt in the Crescent Formation here.)
As I said, the outcrop source for this rock is not known, at least that I've been able to discover, but maybe one of these days...

Variolite from Maguelon, France (www.variolite.fr)

Further note : I was also able to confirm the name, and provenance of this rock with Rowland Tabor, Geologist Emeritus at the US Geological Survey and author of the Guide to the Geology of Olympic National Park. He refers to it in his book (page 67-68) as "globular devitrification structures."  Wow, that's a mouthful.  However, he wasn't able to confirm a bedrock source. That, I guess, I am going to have to find for myself!

Ventifacts

Ventifact, Wright Valley, Antarctica

In 1980, I worked for a season as a field assistant at McMurdo Station, Antarctica. Among my most memorable adventures during those 4 months - and there were many - was a visit to the "Dry Valleys", a series of remarkable ice-free canyons.  I joined a group of scientists doing some sampling in the saline ponds there - see photo below - but also just enjoyed exploring this weird, lunar landscape.

The floor of the canyon was littered with rock, of course, mostly basalt (dolerite) chunks from a series of sills high on the ridges on either side.  What really made them unique, however, was their having been carved by the incessant wind into smooth, graceful objects - sometimes referred to as "ventifacts" or wind-carved stones.  I grabbed a couple of these mini-sculptures but left thousands more...including some perfect stone pyramids 6 feet tall, as smooth as if made from polished granite.

This little pyramid is only about 4 inches tall, but you can see the smooth, polished surface and the faceting caused by sitting in the exact position in the prevailing winds for many decades, perhaps centuries.  I have carried it with me for the past 31 years since that trip, and it is one of my most treasured possessions.

This is a similar process, by the way, to the "Topoliths" in the post below, though this is much harder rock, and polished over much longer periods of time.

Wright Dry Valley, Antarctica 1980