Winter Beaches

Banded Jasper or...?

The beach below my house is primarily sand, esp. during the quiet months of summer, when the surf is at a minimum. But in winter, storming winds and tides throw rocks up onto the beaches, and right now there is a thick layer of pebbles at the tideline. This is perfect for sampling the extraordinary diversity of rocks that characterizes this ancient glacial landscape.

This good-sized cobble attracted my attention today. It was heavy and glass-smooth,  typically a sign of a hard rock like agate or jasper, but with some lovely green and brown banding.  I haven't seen anything like it here before - but that is almost always the case here : rocks deposited on my beach are likely remnants of boulders dropped by glaciers here 10, 000 years ago.

In any case, I popped it into the tumbler - and in a week or so, I'll be able to get a clear look at it. Then it will either go into polishing - or get tossed back onto the beach.

Alki Beach,  New Year's Eve Eve, 2013

Out of the Tumbler

Beach Cobbles, San Simeon, CA

As I posted back in March, I spent a pretty mind-blowing day collecting on the beaches near San Simeon, California, on my way up the coast. Why was it so great?  Because nearly every rock on the beaches there is of something interesting, whether a brecciated jasper, or an interesting agate, or some things that I don't even know the names for. But whatever they are, they have loads of color and striking patterns and polish beautifully in the tumbler.

They do especially well in the tumbler since they are already well-rounded by the wave action. In fact, I usually skip the first coarse grit step in the polishing process and go directly to the finer 120/220 silicon carbide.

I'm still processing rocks I found months ago, and by the time I'm done, it'll be time to head South again to find some more!

Going Crazy in California

San Simeon Jaspers - Naturally tumbled

I do a lot of beach-walking around the Northwest where I live, and often find intriguing and worthwhile rocks mixed in with a lot of junk. So you can imagine what a kick it is to stumble on to a place where nearly every stone is colorful, and beautifully patterned. I had heard about the brecciated jaspers of San Simeon Creek, near Cambria, California and seen some beautiful examples (see Hans Gamma's mouth-watering collection ) but nothing prepared me for a walk along the surf-line yesterday. It was like walking through a kaleidoscope...  In less than an hour I had filled up two cloth bags, and I could have spent days there, seeking out the perfect specimens.

an iPhone sample

The location is the small beach area just south of the San Simeon State Park campground. It's only a quick scramble down the slope and out to the beach. Most of the rocks on the beach itself were tumbler-sized. I'm guessing the big specimens must be somewhere up in the Coast Range headwaters of San Simeon Creek and others. But there are also loads of medium-sized rocks (e.g. 1-4 pounds)  up high on the beach, but I didn't have time to carefully go through them. I'll bet there are some winners there.

But for anyone whose idea of a perfect day is to walk along a wild Pacific beach picking up beautiful stones, you would have a hard time finding anything better than San Simeon.

Beach Surprise : "Plume Agate?"

Beach agate, West Seattle

It's been a while since I was out on the beaches near home - blame it on cold weather and too many buckets already full of rocks, waiting for the polisher.

But on a handsome sunny winter day, I hit the beaches near Alki Point. I am always attracted by color and design, but especially if there is any sense of transparency, e.g. that glass-like quality that suggests "agate."

Here's one I found yesterday, an already well-rounded, naturally polished agate. My first thought was that it was what is known as a plume agate, in which impurities grow into the quartz often in lovely, lacy patterns. But when I took a close look at this, it does not have the typical "plume" patterns, but instead appears to be some sort of brecciated rock into which quartz has filled the gaps. Hard to tell what the green stuff is, but it's clearly fractured and shattered. Now, of course, it is suspended in the quartz matrix. Not sure what to call it, but it's handsome nonetheless.

Surprises

By now, you will realize that my idea of heaven is to wander along local beaches picking up interesting stones and trying to piece together the stories behind them. I often fill a bag within an hour or so, and only weeks, if not months, later get to polishing them. So I can maybe be forgiven for not exactly remembering where I found this one, which emerged from the tumbler today. It is of a free-form yellow jasper together with what looks like a pinkish agate. Pink agate?  Never heard of it before - and as always, I have no idea where this rock originated, thousands of years before it landed on the beach where I found it. Yes, it would be nice to know: I'm guessing there are more like it...

California Treasures

Cayucos Jasper, California

In a post a few weeks ago, I reported that I spent a wonderful few hours exploring the beaches near Cayucos, California, in what turned out to be a mother lode of jasper of every pattern and description. Many were so beautifully rounded that they needed little tumbling, and just the addition of a polish to make them stand out. Well, I finished a batch today - and they are beauties.

There are brecciated jaspers (apparently common along in coast range in this area) and a variety of other colors and patterns. It was probably the single most productive few hours I've ever spent chasing rocks.

Having said that, the beach is NOT the best place for collectors looking for slab-worthy chunks of the stuff - these are all small, and really only fit for those who are content with tumblers. I am one of those, and I am delighted with what I found.  Too bad it's a thousand miles south of here!

Discovery Bay, Olympic Peninsula

I've been in the office a lot lately, or visiting with family - always wonderful - so I haven't been out much looking for rocks. But on a drive back from Port Angeles yesterday I spent a happy hour along the western shore of Discovery Bay. This is one of my favorite shorelines for rocks, since there are rarely any waves, and the diversity is as great as anywhere in the northwest. The site is near the Gardiner boat ramp - a little tricky to find but worth looking for on a falling tide, when the cobble beach is still wet. This makes identifying interesting specimens that much easier. (Best of all is a rainy day, when EVERYTHING is wet and shiny...)

This may not look like much, but as a geologist, I find it tells a pretty interesting story, with bits of green stone in a speckled matrix. I'll know more when I polish it.

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...