Unexpected Fossils

Fossil leaves/needles, Owyhee country

Sometimes, when I am in serious rock-collecting mode, I am picking things up on a whim - a flash of color or pattern might catch my eye. But I generally don't spend a lot of time inspecting each one. Often they just go into the bag for future study. Maybe this is why my car rides so slow when I come home from a trip!

As I have mentioned in previous posts, I was recently collecting in one of my favorite areas, the Owyhee mountains on eastern Oregon. I have been sorting through the specimens I collated, tossing out some, and polishing those that are worth the effort, especially picture jaspers. (see earlier blog post)

But this one was a surprise, different from anything else I saw, and with a pale purple that caught my eye. I tossed it in the bag and only took a closer look today. Breaking off a piece revealed an inner layer  crammed with leaf fossils. I haven't identified them, but they look like conifer needles, twigs etc. strewn throughout a single layer in what I am guessing is rhyolite tuff. A nice surprise!

Christmas Morning

Owyhee Jaspers revealed

One great advantage of a rock saw is that you can non-destructively look inside a weathered rock whose outward appearance is almost nothing like its inside. I have just come home from eastern Oregon with huge amounts of jasper from the Owyhee country, but very rarely are the patterns and colors obvious through the weathered crust. Some things that look intriguing on the surface are dull inside. However, the reverse is also true - some real treasures have no outward sign of what's inside until you break them open - or use a saw.

In the past I had nothing more than a rock hammer to see what was inside - but jasper is really just a natural glass, and often cleaves and shatters in unexpected, and unwanted, ways. I hate to think about the number of really fine rocks that have disintegrated under my hammer! A lot of weathered picture jaspers, for example, are riddled with cracks, which is precisely why there are such great patterns in the first place. These clearly have no business being hammered...

The saw, meanwhile, provides a window into the rock, without risking damage. Now, all I have to do is choose the pieces that look good - like the three above, which I just cut yesterday from very humble fist-sized pieces. The best  go into the tumbler to smooth out the rest of the stone.

After this last trip, I've got many, many more waiting to be opened up.  Can't wait.

Succor Success

Succor Creek Jasper

I'm home and have had a chance to clean up some of my rocks from Succor Creek.  Wow!  I am delighted to have hundreds of pieces of every size and shape. Some I will save for slicing, but I have loads of tumbler material of very high-quality - much better than I got last year.  I am particularly happy to get so much of the Succor Blue Jasper, which I think it stunning.
I haven't shown any here, but I also got some very nice petrified wood fragments - including one very dramatic chunk of swirling black wood. (I'll try and post it later)
I also did some poking around some other areas in SW Idaho, and found a small creek in the foothills around Boise with some stunning football-sized chunks of Yellow/Orange Jasper.  It looks like it may have cracking problems, but I will have to cut into it to see how it holds together. But it has the potential to be stunning.  Two sample pieces below.

Idaho Jasper

All in all, a VERY successful trip. But as I mentioned in my earlier post, next time I go back, I really have to explore some more. There must be vast quantities of hi-grade jasper in those mountains...

Half and Half

To me, every rock tells a story, and I find this one particularly interesting. It is clearly a piece of what geologists call a "contact," a point where two different rock types abut one another. This can be two layers of sedimentary rock, reflecting a change in the depositional environment (e.g. a layer of mud, followed by a layer of silt) or...

(NOTE: if these were sedimentary layers, they would have been laid down horizontally, not vertically as displayed..)

...or they could represent a molten rock intruding into a crack in an existing rock. (in which the orientation could be in any direction) For example, the black rock may be part of a basalt dike that intruded into whatever the gray-green stuff is.

Or maybe there is something else going on. But whatever the story, it was a striking find on the beach this morning...

Structure

Complex cobble, Lincoln Park

Geology was my first major at the University of Washington, and although I eventually got bogged down in the chemistry and calculus, I loved the field trips. We rafted down NW rivers, hiked in the mountains and even chartered a plane for an educational - and spectacular - flight around Mt. Rainier.

My favorite course was one called Structural Geology, in which we used the patterns of rock to understand their history and formation. From a hand sample, we learned to use the patterns of intrusions, folds and colors to trace its story.  It was challenging, but fun.

Since then, I have been fascinated by rocks with complex stories to tell. It may be hard to see in this picture, but the middle of this rock (found this morning in Seattle) is a contact between two different kinds of rock, both with strong, but perpendicular linear elements. One half  is dark with layering along the rock's long axis - the other half is much lighter in color, and with layers at a 90 degree angle. Weird, huh?

Weird...and beautiful.  I don't know what to call it, or how it formed; I'll know more after I've polished it and can study it a bit more.

The Limits of Photography

Biotite on Granite

This is one of my favorite rocks, found - as always - along the shore of Puget Sound. But the reason I love it is not apparent in this photo. The black biotite (mica) crystals that cover the top of this palm sized cobble shimmer with reflected light. It is a layer of crystals, vaguely parallel, but with just enough variation in orientation to catch the light at slightly different angles.

That's a lot of explanation for a simple rock, not well-photographed. I may need to try some other technique to capture the glittering mica crystals. Trust me, it's a beauty....

Heading East - the FAR East...

Black jasper/agate, Puget Sound

I thought I would post one more local stone (from a Puget Sound beach) before I leave this weekend for Indonesia. It is a highly fractured, but rather lovely, agate-like piece, semi-transparent and hard.

My destination is the island of Sulawesi, and my mission is to document the life history of a unique bird that lives there - the Maleo.  But in the little reading I have done on the island, I have learned that it also has a complex geology including a mix-up of volcanics, and both ocean floor and continental  rocks.

I have no idea whether I'm likely to find any collectible rocks, but as always, I will keep an eye out... Back in a couple weeks.

Complex Stories

Banded Agate/Jasper, Olympic Peninsula

When I studied geology at the University of Washington, my favorite class was one called "Structure" in which we tried to piece together the sequence of events that have altered rocks and landscapes by reading the stories within them. If one continuous layer in a sedimentary rock is offset along a plane, for example, you could infer that a fault had shifted AFTER the deposition of the layers. (see the faulted jasper in my August 25 post). Sometimes, however, multiple events can overlap, creating a very confusing picture.

That's what's happening with this rock, which I found among beach cobbles on the Pacific Coast of the Olympic Peninsula. I'll call it an agate/jasper (or "jaspagate" as I've seen it written elsewhere) which is simply another name for a rock that has features of both: the transparency of agate and the opacity of jasper.  Whatever you want to call it, this small pebble seems to tell the story of fracture and fill: an existing red jasper was fractured, possibly several times, and injected with quartz solution - both clear and vivid red. How did this happen?  I have no idea, but whatever the story, its this complexity that helps create this handsome visual pattern, one with tantalizing hints of the paintings of Jackson Pollock.

Faux Feces

Pseudo-coprolites, Salmon Creek, WA

Coprolite is  fossilized dung. (Greek : copros = dung, lithos = stone) It is a rare, but oddly compelling, fossil, especially if it can be shown to be from an exotic source, e.g. dinosaurs.

For many years, collectors have been finding what looked like coprolites in abundance along Salmon Creek in southwest Washington State.  I was there recently, and easily found dozens of these things.

However, most paleontologists say these are not coprolites at all, despite their similar morphology, but some sort of unexplained mineral deposit. Coprolites, it turns out, contain fossilized remains of plants (or bones and hair for the carnivores), or whatever the diet of the animal which left it.

These "psuedo-coprolites," by contrast, show no such structure, and their chemical signature is all wrong.

Too bad.  I think my grandson would love to have a piece of real dinosaur dung...!

Fractured Jasper

Fractured Jasper Pebble, Puget Sound

Jasper is one of the most common, colorful rocks among the beach cobbles of Puget Sound. It is composed of micro-crystalline quartz (e.g. its crystal structure is too tiny for the eye) and therefore is very hard and takes a nice polish.  Often the samples I find are broken, fractured or badly-shapen.

This one, however, had both a nice shape, and a handsome fracture pattern similar to the "crackle" in pottery glazes. Despite its symmetrical shape, I did not cut it, but simply polished the stone as I found it, which rounds out sharp edges, but otherwise changes the rock very little. To be honest, I enjoy these "natural" shapes much more than cut cabochons so popular in the jewelry business.  It will never be a necklace, but I enjoy it all the same.

Rock Revealed

Unknown rock, polished

A month ago, I posted about a trip to the outer coast of the Olympic Peninsula, and about the variety of rocks I found among the beach cobbles - most specifically this one.  I noticed it as distinct from all the rest even in its rough, straight-off-the-beach state. (see July 28 photo) .

Now, a month later, it has gone through the polishing cycle, and its really unusual patterning has been revealed.  It is hard, and has taken a good polish, indicating something silica-rich (rather than a softer, sedimentary rock) but beyond that, I haven't got a clue. A strange jasper formed at the boundary of two rock types?  The multi-colored zigzag pattern which is its most striking feature, makes it look like it was liquid at one point.

Anyhow, whatever its name - it's a beauty. But like most of the others I find, from an unknown source.

app. 3" long

Big Stories...in Miniature

Mini-faulted Jasper

I have just finishing polishing some recent finds from beaches along the Puget Sound shoreline that I've gathered over the past few months.  Two of my favorites are here.  The first, above, is one I like because it shows big ideas -- in miniature.  The rock is only 1.5 inches tall, but clearly shows the offset layers caused by movement along a very small, but obvious, fault. This phenomenon is common enough in nature, in scales both micro and macro, but it is not often displayed with such precision in a rock you can hold in your hand.

Petrified Wood

This is also a handsome miniature, an inch-long pebble of petrified wood. Not wildly colorful, but displaying the layers of both bark and what I can only assume is some darker heartwood. I knew I had a beauty when I found this one, but had to wait a month for it to go through the tumbling stages.

Both rocks beg the same question I mused about in a previous post: where could they have come from?  Found on a Seattle beach, both could very likely have been scraped off an outcrop in the BC coast range, or somewhere on Vancouver Island, by the massive glaciers of the Pleistocene. They could have been worn down to pebble size by ten thousand years of surf and tide. I'll probably never know.

The truth is, I just get a kick out of imagining the journey these rocks have taken to my desktop. Go figure.

In the Trenches

I am fairly new to rockhounding, and rely on published guides to help steer me towards locations with interesting rocks.  I have several :

Gem Trails of Washington by Garret Romaine

Rockhound's Guide to Washington Vol. 1 & 2, by Bob & Kay Jackson  (ca. 1970)

Both cover a lot of the same ground, but help a beginner like myself get started.

The downside is that many of the areas described in both books have been pretty well picked over by generations of rockhounds before me.  What that means in practice became clear to me this week, when I went to explore Salmon Creek near Toledo, Washington.  Known in the past for its carnelian agate and jasper, Salmon Creek may still produce new material, especially after winter storms scour the watershed.

Carnelian/Agate, Red and Green Jasper, Salmon Creek

To me, however, Salmon Creek looked like a war zone. Pocked with craters and rock piles, this was as close to industrial rockhounding as I've ever seen, with the stream diverted, and every gravel bar turned upside down. Not only did this look like a waste of my time - and it was - it was disheartening to see the creek degraded this way. I know there are State rules for digging in and around streams, and although I don't know all those rules, I'm sure most of them were broken here, certainly in spirit. If there were once salmon fry in this stream, I doubt many of them survived this onslaught.

In the end, I bushwhacked up the river a mile or so, and found a spot where, although there were still pits and piles, there was not the devastated look of the lower, more accessible, parts of the river. I found a few nice pieces of agate and lots of lovely green and red jasper. I'm sure others have found better before me, but at what cost? I did no digging, or screening.

This experience made me resolve to search out other, less-publicized locations, and maybe find a few of my own. Either way, I will do everything I can to minimize my impact on the environment around me.  I have never been a fan of open-pit or strip mining: why should it be acceptable for rockhounds?

Far, Far, Away

Polished beach pebbles, Chiloe Island, Chile

Yes, I know, this blog is supposedly about Pacific Northwest rockhounding, but it is also a chance to highlight some of the oddballs in my collection.  Last year, I spent 2 months working on the island of Chiloe in southern Chile. While there, I was told by locals - who knew about my interest in rocks - about a nearby beach with "beautiful stones." Intrigued, I had them take me there. It was a nondescript little bay, like many others along this ragged coast, but I did notice that the beach pebbles had a striking variety of patterns, and the smoothness and heft of silica-rich stone. I collected a few pockets-full (God, how I wish now that I had gotten more!) and brought them home to polish.

The six samples above show how wildly different the stones were, in patterns and colors, yet all had the same relative hardness, and shine. But none are recognizable as agate (no transparency) or jasper: some have what looks like sedimentary layering, while others have no linear structure at all.  Clearly there is something interesting going on in the geology of this bay, but I have not been able to find any references online.

If anyone can suggest what these rocks are, I will tell you where I found them. I only wish I had an excuse to go back...

St. Kilda Oddity

 Granite/Dolerite Breccia, St. Kilda, Scotland

I collected this rock two years ago on the remote island of St. Kilda, off Western Scotland. It is about 9 inches long, about the size of an enormous russet potato.  I was stunned by the structure of the rock, composed of angular blocks of dolerite (Basalt) "floating" in a granite matrix. This was the largest one I could carry - but much of the island ( a World Heritage historical site) is made up of this stuff. No gem value, obviously, but just a wonderful piece of geology.