Just Before Dark

The sun was shining today - a rarity in March! - which makes beachcombing difficult.  Everything is more reflective, and although glassy rocks like agates show up well, others do not. So after the sun went down I took a short walk on a nearby beach, and brought home just a pocket full: a couple of nice petrified wood and jasper pieces - and a spotted thing I can't identify.
I am heading away from familiar beaches tomorrow and looking for agates in the southwestern part of the state, which may involve a lot of probing and digging. We'll see how THAT goes...

A Morning's Work

Agate, Jasper and.....?

A half hour walk on the beach near my house proved very productive today - ending up with a bag I could barely manage to carry back to the car.  Some of the highlights are pictured here - a banded jasper, a moss agate, a petrified wood and some other things I wouldn't dare to name... All will go into the tumbler this weekend - and if I remember, I'll post the polished forms next week.

Hiding From The Wind

Polka Dot Jasper/Agate, Elliot Bay

The wind has been blowing A LOT lately, which makes collecting difficult along my close-by locations along eastern Puget Sound. Hard to see much, or stay dry, when waves are breaking along these normally-placid shores!  Happily, I know one secret cobble beach, on a protected shore of Elliot Bay, where I often find some interesting things.

So on a recent blustery day, I spent a few minutes picking along this quiet beach and found some nice things, including this unusual polka-dot jasper-agate. I've never seen anything like it in the area but, as  always, its actual provenance is a mystery.  But I'll certainly be on the lookout for more!

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.

Using the "Search Image"

Petrified Wood, Alki Point

When I patrol the beaches near my home, looking for colorful or unusual rocks, I try to keep a mental image of what I am looking for, what scientists call a "search image." This refers to having a visual sense of what you're after when you set out, which can give you an advantage in spotting one specific kind of rock among thousands. Normally, I look for bold patterns, or bright colors - the easiest things to see. But today I made an effort to look at black rocks. My goal? To find specimens of petrified wood.

As I have mentioned in earlier posts, there is a form of black petrified wood that I have found many times on local beaches, though normally as small cobbles that reveal their patterns only after polished. I have no idea where the rock originates, but I am guessing it is somewhere relatively nearby, simply judging by the relative abundance of the stuff.

So I set out today with the idea of concentrating on finding these pieces of dark wood. This may be why I found this piece within 15 minutes of searching the beach, by far the largest piece of petrified wood I have ever found along the shore.  Did my "search image" make the difference, making this rather drab piece of rock stand out?  I think it did.

Though this piece looks drab now in its unpolished state, I will try and post a picture of it after polishing - look for it a few weeks from now. Until then, I will probably be back looking for other pieces of streaky black rock...

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....

Discovering Ancient Forests

Petrified Wood, Puget Sound

Every time I open up the tumbler at the end of a polishing cycle, it's like Christmas all over again. Some stones, especially soft sedimentary rocks, never take a polish - but those that do can reveal some stunning patterns and colors. And one thing that I am always happy to see is Petrified Wood. These came out of my tumbler just this morning, pieces of wood I have found along the beaches of Puget Sound over the last few months.

On the beach, they are not always easy to recognize. Although they take a beautiful polish after the fact, they show none of this luster and translucency after they've been tumbled in the surf for a few thousand years. But somehow these caught my eye anyhow - and I'm glad they did.

I have begun to see recurring styles of wood: jet black with tan bark remnants, yellow/orange with strong ring patterns etc.  To me, this suggests a couple of specific (but unknown to me) source locations in the Puget Sound basin.  Logic dictates that the more abundant a certain rock type is, the closer the source. (Or maybe it means that some distant sources are simply more productive)

Wherever the source, they are beautiful.