Well, actually, my intrepid companion was there, but he paid more attention to the planes.

We’ve been to St. Edwards State Park before.  It’s one of my regular haunts – I try to get there at least once a summer.  Convenient, y’see, and some of the best pebble-hunting grounds around.  There’s a place at the end of the Grotto trail where you come on a nice sandy bit o’ beach, with riprap trapping nice pools of water with pebbles in.  It’s a fantastic place to linger on a summer afternoon.  Little cold for fall, though, which is too bad, because there’s nothing like rolling ye olde pants up to the knee and plunging into the pools in search of pretty pebbles.  Last year, I even found some bits of glorious gray schist washed up, which is rare around Lake Washington.  This time, I found a few calico pebbles and a foliated chunk of something-or-other that I might, someday, be able to identify for certain, lingering close enough to the water’s edge to prevent foot-freeze.

Here’s a view of mah pebbly beach with foamy waves:

But the pebbles weren’t half as exciting as being able to recognize geologic formations all by myself.

Usually, when I write up these missives, I have some sort of guide around.  I’ve got a book or a website that’s discussed the geology in enough detail for me to puzzle things out, and thus sound like I know what the fuck I’m talking about when I babble about them.  Not true in this case!  St. Edwards has too much damned biology hanging about to be a huge geologic draw.  You have to really hunt for areas of exposure.  Luckily, my intrepid companion found one whilst we were searching for a spot where we might be able to see the seaplanes land despite all the damned trees.  There’s a narrow break between the trees, a steep scramble, a little bench of beach, and if you turn around, glory be!  There’s some bare geology:

It’s even got pebbles in!

Okay, so what are we looking at?  Later exploration revealed it’s gotta be some of that yummy Olympia non-glacial stage stuff we talked about when exploring Discovery Park.  How do I know that?  We’ll get to the smoking gun a bit later.  For now, let’s savor the novelty of having actual dirt exposed in western Washington.  This bank has a few items of interest.  Such as these lovely pebbly layers:

Yes!  I finally remembered a quarter for scale!  Good thing I hadn’t spent it on junk food at work.

Isn’t that a pretty bit of white quartz down there in the bottom left?  As for what put the pebbles there, it would take further exploration – and possibly some malicious mischief done to interfering trees – to determine if those are old stream beds or lake shores.  But we do know, from work actual geologists have done, that these sediments were laid down in a flood plain before the glaciers came.  We get lots of sand, lots of pebbles, and some gravel:

And here’s a full view of the bank where all these lovely layers may be found:

I’ve never been so happy to see a plain ol’ dirt bank in my life.  Geology changes things.  It makes the ordinary stuff seem almost ethereal.  Even the drab bits of earth are beautiful when you know they’ve got a story to tell you.  Okay, so they’re having to speak to me in “See Spot deposit some gravel!” language right now, but the point is, I now understand that I’m seeing more than boring old rocks and dirt.

So how can I be sure that this is the famed Olympia non-glacial stage stuff?  Simple.  For one thing, we’re down close to sea level, and that’s where the Olympia etc. deposits are.  Secondly, there’s a ginormous freaking clue up the Seminary trail:

That, my darlings, is a big bare bank of our old friend the Lawton Clay.  And we know the Lawton’s resting above the Olympia etc.  Ergo, Olympia down below.  My intrepid companion just gave me a bemused look when I told him to strike everything I’d said about the previous bank possibly being Esperance Sand.  (I’d gotten my elevations and strata mixed up, until I saw this beautiful exposure.)  Then he watched me get dirty in the name of geology.  Sometimes, I wonder why he puts up with me.

All right, so if I fucked up badly enough to think Olympia etc. was Esperance, how can you trust my word this is the Lawton Clay?  Well, let’s do some field work.  Is it thick?  Check.  Is it gray?  Check.  Is it clay?

Certainly chunks apart like big blocks of wet, nearly-pure clay when it falls, don’t it?  But let’s pick up a chunk to see:

You could make bricks, pots, and little sculptures from this stuff.  It’s smooth and tacky and sticks to your fingers like all that lovely modeling clay you got to mix up and splat your friends with in elementary art classes.  Yup.  That surely do look like clay!

So, if that’s the Lawton, that means we were indeed busily putting quarters all over the Olympia etc. deposits, and further up the hill, we should find…

Could it possibly be…

Yes!  Esperance Sand!  Too bad we came upon it as the trees were busy filtering out very nearly all of the remaining sunlight, but at least Handheld Twilight mode allows us some decent view of things.  Glacial outwash, baby, yeah!

We can even see some pebbles in there.  Fun times!  And a triumphant moment.  Do you know how hard it is to find any exposure of this stuff along the trail?  Up there, where things flatten out, the damned biology has taken over every available space.  There’s just a few spots where a bit of over-steepened bank caves away from the roots, and then a glimpse, a mere glimpse, of glacial outwash goodness.

As for the Vashon Till, it’s still MIA.  Probably buried under 5 billion tons of bark.

So there you have it.  Actual geology, despite the best efforts of the biology to hog the spotlight.

Yup.  We finally made it to the actual geology of Discovery Park.  Be amazed.  Be very amazed.

I don’t remember seeing South Bluff the first time I esplored, way back in 2000.  I’d abandoned my best friend to the vicissitudes of the big city, because he’d decided after our stint at Ravenna Park that he’d had enough of nature, thankseversomuch, and desired the wilds of a two-story Barnes and Noble.  I handed him the keys to the rental car, hopped a bus, and headed off to do me research.  I’d set an important scene at Discovery Park, y’see, and spent my time there busily trying to find locations that matched what I needed.  I did make it down to the beach, but all I remember from that excursion was the lighthouse, the washed-up jellyfish, and the baby seal – my first! – that posed so prettily for me.  I didn’t make it much further than the point – had to get back up the hill and catch the bus back to the hotel.

So the first time I saw this:

– was May 2007, after I’d moved up here for good and all. 

Geologists in the audience may begin salivating… now. 

I spent quite a bit of time with that bluff that sunny afternoon, long enough for the sunlight reflecting from both water and cliff to burn me a nice bright red.  I remember patting it, delighted with its patterns, the stolid solidness of it.  I’d seen the signs up top saying it was unstable, but it was hard to believe them at the time.  Sure, people could (and unfortunately did) carve all sorts of nonsense into it, but then, they did the same thing to the lithified dunes around Page, so it didn’t occur to me I wasn’t looking at rock so much as a coulda-been-rock-someday.  I’m not used to what amounts to mud forming a vertical cliff, y’see.  First bluff I’d ever seen in my life. 

Click to embiggen that photo.  Take a closer look at it.  Note the trees around its shoulders.  See how they lean every-which-way?  See how young they are?  This is our first hint that the “unstable bluff” signs weren’t lying.  Those trees occasionally get to take the ride of their young lives as the slopes below them go merrily slip-sliding into the sea.  Then they add to the driftwood population in Puget Sound.

Hard to believe you’re looking at a glacial landform, innit?  Allow me to show you it:

Okay, part of it.  And this isn’t really the glacial bit.  I can ‘splain.  Or at least sum up.

So this one time, before the Cordilleran Ice Sheet, there was this floodplain.  Puget Sound wasn’t so much as a gleam in a glacier’s ice back then, although the ice was gathering itself up in British Columbia and getting ready to make a run for the border.  What I’m playing Vanna with up above was laid down in warm climes between 22,400 and 18,400 years ago during a time known as the Olympia non-glacial stage.  When Canada next goes under the ice sheet, it appears we’ll have a while longer to enjoy our pleasant marine climate before we, also, are covered under several thousand feet of ice.  Woot!  Suck it, Canada!

It’s really lovely stuff.  Look at the pretty patterns:

And a closer look:

You can see the plant debis weathering out of the middle layer.  If you listen closely, above the crash of the surf, you will hear it cry, “I coulda been a fossil contenda!”

This stuff is hard.  When you pat it (yes, I pat rocks, you gotta problem with that?), it gives you a nice solid sandstony feel.  It’s not rock yet, but it’s certainly headed that way – some bits more than others:

This gives you a good view of what you’re dealing with – some bits are more sandy, some more silty, even though it’s weathered to a nearly uniform color.  Some bits are harder than others, and resisting erosion a little more successfully.  But I’ve got bad news for it.  The waves that lap up against the bluff at high tide are cutting the ground right out from under it:

That mushroom-cap appearance does not bode well for the bits of bluff above.  Here’s a closeup of what those nefarious waves are up to:

Oh, yes, indeed: a nice, smooth curve carved into the wanna-be rocks, which is just an invitation to gravity.  The bluffs are eroding away at the rate of around 80 feet per century.  Eventually, the Visitors Center’s gonna have a nice Sound-front view.  Elsewhere, some homeowners have already seen their property values decline right into the sea.  You want long-term stability, don’t build on a bluff.

And if you think that’s some impressive wave-action, check out the cave carved round the other side:

So, dear Olympia non-glacial stage sediments, this is your fate:

One day, the waves are going to cut your feet from under you, and gravity shall make sure you have a nice day on the beach, where you shall be resurrected as sand, perhaps one day to rise as a bluff once more. 

By now, my darlings, you might have noticed the lovely wavy patterns in all these photos.  Movement on the Seattle Fault may have something to do with it; so could ancient landsliding and that bloody great 3,000-foot thick glacier sliding over it.  Things that start out all straight and neat in nature routinely end up crinkled, just like my laundry.

Speaking of faults, I think I found a small one, and it’s not merely my personal fault of not using a damned iron.  The experts can tell us if I’m right:

Could just be funky erosion, I suppose – there’s not much offset that I can see – but it could also be a baby fault saying, “Oh, hey, I’m not-quite-lithified sediment, and there’s a shit-ton of weight on me!  Ow!”

And what, you may ask, is weighing so heavily upon our lovely Olympia non-glacial stage sediments, other than more Olympia non-glacial stage sediments?  Why, that would be the Lawton Clay!  Here’s a shot stitched together by my intrepid companion, a slightly larger version of the sea-cave shot above, showing the Lawton Clay bearing down upon our poor, innocent Olympia non-glacial etc:

The Lawton Clay is that forboding dark-gray stuff, although bits of it seem to have weathered white up there.  The Lawton’s got calcerous concretions and vivianite in it, some of which might provide those chalky-looking patches (although from what I understand, vivianite’s only chalky white when it’s fresh).  What you’re looking at up there is the footsteps of doom.  You see, this stuff probably got laid down in a maclargehuge lake.  And the reason for a lake being there is, the Puget Lobe of the advancing Cordilleran Ice Sheet had blocked the northward-flowing rivers that drained out the Strait of Juan de Fuca at the time.  It came closer, and closer, and…. left us with a slippery slope, that’s what.  Because, you see, the Lawton Clay likes to fall down and go boom.  See, I can prove it to you:

We found chunks of it all over the place.  And ’tis indeed clay – you could practically make pots with it.  Should you find yourself on the beach there, go ahead and pick some up.  You can chunk off bits quite easily and moosh them in your fingers.  Look, some of it’s even pre-chunked for you:

You might notice this clay’s rather prone to fragmentation.  And anyone who’s dealt with clay knows how slippery it gets when wet.  Now consider that a good part of the bluff’s trying to balance on it, and, well, you know – stuff happens:

Big part of the cliff fell down and went boom.  For some inexplicable reason, probably having to do with playing with clay, then photographing clay, then realizing “Oh, fuck, the tide’s gonna eat me if I don’t move!” I didn’t get a full-length view of the slide, but the above is the nice scarp, and down below here you can also see a nice clean shoulder of (probably bloody annoyed) Olympia etc., and then the very top of the talus slope formed by the slide:

Here’s a nice close-up of the light-colored bits freshly broken:

Respectable little landslide, that.  Wasn’t there last time I visited, and might not be there when I go back.  That’s the nature of the bluff.  It’s like a Thanksgiving turkey that nature keeps carving more bits off of.

When you get to the very tip-top of the bluff, you’ll see that the glacial story didn’t end at a bloody great lake depositing clay all over the place.  No, indeed.  You’ll find the Esperance Sand, a nice thick bit of glacial outwash deposited by meltwater streams flowing merrily south as the Puget Lobe advanced on Seattle with the coldest of intent.  There aren’t hugely good exposures from this angle at South Bluff – at least, not with the incoming tide driving you right against the cliff – but I do believe this is a nice bit of it:

Isn’t that bedding pattern lovely?

The Esperance Sand is, indeed, lots of sand and silt.  It got draped all over the landscape right around 18,000 and 15,500 years ago, before the glacier caught up to it and buried everything under a nice coating of thick, heavy Vashon Till.  A lot of that till has eroded away near the Sound here in Discovery Park, but there are still places where you can see it.  You’ll know it when you encounter it: it’s hard, weighty, dark-gray stuff filled with rocks.  In places, it’ll be overlain by yet more fluvial deposits left by yet more meltwater streams as the 3,000 foot ice sheet saw Olympia, said “I came, I saw, I’ve bloody well conquered enough of America, thankyooverymuch,” and headed back for Canada.

One thing I’m pretty sure most people don’t realize as they explore the nice, sandy, somewhat duney meadows atop South Bluff is that all this nice sand has nothing to do with the sea.  The sea wasn’t even there for a very long time, and when it was, didn’t hit the top of the bluffs.  No, that’s all stream work.

Amazing, innit?  So take a good, long look at ye olde bluff, because while it has a long and busy past, it’s got a short present and a non-existent future:

Tip o’ the shot glass to the Hiking Guide to Washington Geology and Landslides and Engineering Geology of the Seattle, Washington Area, without whom this post would’ve been impossible.