Rocks. Just rocks.

I never tire of looking at rocks. The bones of the earth, and its history, too often taken for granted. This batch of photos is typical of many of our local shores; flat sandstone, scattered with glacial erratics and pock-marked sculptures, carpeted by seaweeds green and brown, inhabited by millions of small beasties.

Smallish erratics, smaller glacial droppings, and sandstone sculptures. These remind me of petrified jellyfish.

The three basic types of rock seen here.

Much of the shore is paved with this flat, layered sandstone. On top, rocks brought down by the glaciers from the mountains that make up the spine of the island. And these lumps of granier sandstone, in fantastic shapes.

This section is sandstone covered with brown seaweed.

Triple-decker sandstone sandwiches.

One large patty for another sandwich. About a metre across.

And everything is coated with tiny barnacles, resting at low tide, busily fanning through the water when it returns. In every crevasse and seam, periwinkles are busy chomping away at the rock. And almost forming part of the rock itself, oysters are glued here and there. More about those oysters, tomorrow.

~~~~~~~~~~~~~~~

Nunca me canso de observar las rocas. Forman el esqueleto de la tierra, y nos cuentan de su historia; son la base de todo. Este grupo de fotos es típico de nuestras playas por estos rumbos; piedra arenisca formando la base, salpicada de bloques glaciales y esculturas erosionadas de piedra arenisca, con una alfombra de algas marinas cafés y verdes, el hogar de una multitud de criaturitas marinas.

Fotos:

1. Unos bloques glaciales no muy grandes, y muchas piedras más pequeñas, también dejados por los glaciares. Las esculturas de piedra arenisca aquí me hacen pensar en medusas petrificadas.
2. Los tres tipos de rocas que vemos aquí. Un pavimiento de piedra arenisca fina, plana, con capas encimadas. Encima, rocas que vinieron desde las montañas que forma la espina dorsal de la isla. Y luego esas masas de piedra arenisca, ésta más granosa, y que toma formas fantásticas.
3. Una sección de la playa cubierta de alga marina café.
4. Parecen sandwiches o hamburguesas. De piedra.
5. Otra hamburguesa, sin el pan. Mide aproximadamente un metro de diámetro.

Y todo está cubierto de bálanos chicos, descansando ahora que la marea está baja, muy ocupados agitando el agua buscando su comida cuando sube. Y en cada grieta y espacio entre rocas, caracolitos Sitka littorina trabajan tallando la roca. Y casi haciéndose parte de la misma roca, se ven muchos ostiones. Más acerca de esos ostiones, lo dejo para mañana.

Pondering sand patterns

I watch where I step on the beach these days; I don't want to crush innocent critters just going about their business, not expecting a big foot to come crashing down.

So I noticed these patterns in the sand.

Wave patterns. And a snail trail. (A bit below the nose of the sleeping rock.)

The waves leave different patterns on every beach and on separate sections of the same beach; some smooth, some rippled, some deeply furrowed, like these.

Smooth sand and great blue heron tracks.

The great blue heron has 4 large toes, 3 pointing forward, one behind. The longest toe is the leading one, in the centre-front. The hind toe is shorter. So why does the footprint show a long hind toe mark? Does he put down that toe first, then drag it forward before the others make contact? I'll have to watch the next heron's gait to see.

Herons have a tiny bit of webbing between the toes, near the centre. It doesn't show in the tracks.

Gull tracks, coming and going.

Gulls have the 4 toes, but the hind one is just a stub. They also have webbed feet, but their tracks don't show this. Mallard tracks do. Mallards are slightly heavier (1,000 - 1,300 gm.) than our common glaucous-winged gull (900 -1,000 gm.) ; is  that the reason, or is it that they're more flat-footed than gulls?

And this is sand, too: old, old sand, turned to stone.

Sandstone ripples.

The ripples here intrigued me. They're not wave patterns, but rather a series of layers, each eroded back to show the layer beneath. Yearly deposits of sand, maybe. Or was the sand laid down over much longer times? Periodic flooding events, maybe?

But one thing more: look at all those pockmarks, the little holes in the rock. They're jam-packed full of snails.

Sitka periwinkles. Hundreds of periwinkles. 

And all the sandstone rocks around, every single one, is peppered with these tiny snails. Millions upon millions of snails in a short length of beach. Careful where you put your feet!

~~~~~~~~~~~~~~

Me fijo bien donde pongo los pies en la playa; no quiero machucar ninguna criatura inocente que anda atendiendo a sus propios negocios sin esperar que un pie gigante le venga encima.

Y me llamaron la atención estos diseños hechos en la arena.

Foto #1: Canales formados por las ondas. Y una huella de un caracolito marino. (Mira un poco abajo de la nariz de esa roca durmiente.) Las ondas hacen diseños distintos en cada playa y hasta en diferentes partes de una misma playa. Algunas arenas son lisas, otras con onditas, otras con canales como estos.

Foto #2: Las huellas de una garza azul en la arena lisa. La garza azul tiene 4 dedos; 3 en frente, uno atrás. El dedo más largo es el del centro en frente. El dedo trasero es más corto. ¿Porqué entonces en la huella que deja el dedo trasero se ve mucho más largo? ¿Será que baja primero ese dedo, lo arrastra por un momento antes de bajar la pata por completo? Tendré que observar como camina la próxima garza que encuentro.

Las garzas tienen las patas palmeadas, pero solo un poco en el centro, y no se nota en las huellas.

Foto #3: Huellas de gaviota. Las gaviotas también tienen cuatro dedos, pero el trasero es muy corto y no llega al suelo. También tienen las patas palmeadas, pero esto no deja huellas. Los patos mallard sí dejan lo palmeado bien marcado. Tal vez sea porque los patos pesan un poquito más (1,000 a 1,300 gm para los patos, 900 a 1,000 para las gaviotas) o porque los patos bajan la pata con más fuerza. ¡Tantas preguntas!

Foto #4: Y esto también es arena, arena muy vieja; piedra arenisca. Las ondulaciones no son diseños causados por las ondas. Más bien son una serie de capas, cada una dejando a la vista la de abajo. Depósitos anuales de arena, tal vez. O tal vez tomó más tiempo, como si fuera por inundaciones periódicos. 

Una cosa más: mira esos pocitos en la piedra. Están llenos de caracoles.

Foto #5: Caracoles Sitka littorine. Cientos de caracoles.

Y cada piedra arenisca en toda la playa, todas están cubiertas de estos caracoles. Millones y millones de caracolitos en un tramito corto de la playa. ¡Fíjate bien donde pongas los pies!

No hurry

The rocks just sit there. The tide comes in, the tide goes out; rain and wind pound the shore, sun bakes it, seaweed grows and dies, crabs and sea urchins come and go. The rocks just sit there.

Stories Beach glacier tracks.

Well, not really. Our sense of time is off. We're so short-lived; everything has to happen NOW!

Back when the island was young, a dying tribe of glaciers raced down into the ocean, scraping the ground as they went, dropping the rocks they had collected up on the mountain tops as they melted.

Abandoned erratic

The activity didn't stop when the ice had joined the sea. Wind and water took up the task and have pounded the shore for thousands of years, shaping soft sandstone, rolling, cracking, and polishing harder rocks, sometimes sweeping the shore clean of encroaching seaweed, sometimes nourishing it. Stand on the edge of the water on a pebbly beach and listen; with each wave, you will hear the stones rolling back and forth.

Sandstone outcrop among harder, tide-polished stones.

The shoreline is still changing. From year to year, I see the differences; a new spit at Oyster Bay, freshly shattered layers of sandstone, a change in the seaweed cover on Stories Beach, a new crop of barnacle and oyster scars, deeper muck below an estuary; sand and stone and their living guests responding to the world around them. On their own schedule.

~~~~~~~~~~~~~~~~~~~~~~~~~~~

Las rocas no hacen nada. No se mueven. Sube la marea y baja, el viento y el agua golpean la costa, el sol la quema, algas marinas crecen y se mueren. Cangrejos y erizos de mar van y vienen. Las rocas se quedan tranquilos y en paz.

Fotos:

1. Huellas de los glaciares en la playa Stories.
2. Bloque errático, abandonado por el graciar.
3. Piedra arenosa entre piedras pulidas.

Bueno, no es cierto que las rocas no se mueven. Nuestra idea de tiempo anda mal.

Cuando la isla era joven, una tribu de glaciares moribundas corrieron hacia el mar, raspando el suelo en camino, dejando caer las rocas que habían juntado, allá arriba en las montañas ahora que se estaban derritiendo.

No cesó la actividad cuando los glaciares se habían hundido en el mar. El aire y el agua empezaron su obra de moldear lo que los glaciares abandonaron. Durante miles de años han seguido tallando la piedra arenosa, rodando y quebrando y puliendo las rocas más duras. Hoy en dia, párate justo a la orilla del agua en una playa de piedras chicas cuando baja la marea: oirás el rumor de las piedras rodantes.

La costa sigue cambiando. De un año al otro, veo las diferencias: una lengua de tierra nueva en Oyster Bay, estratos de piedra arenosa recién rotos, un cambio de la vegetación de algas en la playa Stories, nuevas incrustaciones de conchas de ostiones y bálanos, más lodo orgánico a la boca de un rio: la arena, la piedra y sus huéspedes vivos responden al mundo a sus alrededor. Todo a su tiempo.

Find the turtle, too

 Stony family, basking in the sunshine ...

Sandstone beasts, Stories Beach

~~~~~~~~~~~~~~~~~~~~~~~~~~~

Una familia en piedra arenosa, tostándose al sol en la playa.

Of stones and crabs

When I go out without a fixed end point, I usually go north or west, away from the cities and the noise, the road crews and the traffic. This Wednesday I decided to break the pattern and head south. I didn't know where I was going; somewhere beyond Comox, 45 minutes to the south of my place; somewhere between the Comox valley and Union Bay, probably.

I'd barely gotten to Royston when I saw the sign: Royston Seaside Trail. Destination found. I drove to several spots along the trail, going down to the shore in each spot. The tide was low and going out; I walked to the water's edge in each location.

The setting. Royston is on the far side of a bay with Comox and Courtenay on the other two sides.

The shore is flat and stony; there was no sand, some mud. Very slippery mud. After three steps, it slithered away underfoot and almost threw me. I moved back to the rocks.

The stones here are hard, angular, sharp-edged, firmly glued to the underlying mud. And everywhere I looked, tiny crabs were scuttling about, sometimes stopping to threaten me.

It was low tide, and the sun was hot, so I was surprised to see so many crabs out in the heat; usually they find shelter under stones or seaweed when the water goes away. Not here; maybe because the stones are so solidly embedded, maybe because there was almost no seaweed, except for a few patches of bright green stringy algae and the occasional lonely rockweed.

In an area with rounder rocks, a green shore crab finds a bit of shade.

This poisonous-green algae formed mats here and there. Possibly Urospora pencilliformis.

I collected a stone with barnacles for my snails at home, and wrapped it in some of the green algae; the crabs and hermits would appreciate it. Before I wrapped it, though, I shook out the seaweed, scattering tiny snails and crabs. Still, a dozen miniature shore crabs somehow made it home unobserved. They're in my tank now; I'll have to return some of them (the ones I can catch) back to the shore.

There were crabs everywhere. In this patch, I can see at least 6 crabs; more will be hidden under the rockweed and hair algae.

The other residents of the shore seem to be mostly barnacles and snails, and a few oysters. I looked, but found no worms, no anemones, no tiny swimmers. And surprisingly, no hermit crabs, which are usually in abundance where there are many snails to provide shells.

This crab molt probably came from lower in the intertidal zone. A young Dungeness crab, Cancer magister.

Another Dungeness crab, this one underwater. So clear the water!

There were a few patches of sandstone like what we find around Campbell River.

The trail website suggests that many of the rocks on this beach are not original to the site.

Starting in 1911, steam locomotives hauled logs from logging camps throughout the Comox Valley to the Royston log dump. ... Where it approaches Hilton Road, the railway grade was constructed in the intertidal area. From the end of Chinook Road, a mile long wharf extended into the water.  Logs were tipped off the wharf until the early 1950s when the railway stopped running. ... The wharf was taken down and replaced by a breakwater in the 1950s. ... The rocks that can be seen within the intertidal area during low tides most likely originate from the fill material placed to construct the railway grade. (Royston Seaside Trail website)

More rocks, the breakwater, and - what's that?

About those rusting hulks, tomorrow.

New word: tafoni

Chapter Number Umpteen in "Why I love blogging."

I've been looking at holes in sandstone for a few years, wondering, not knowing how they were made. Twice, I've written posts about them, here and here, mostly full of questions.

And I've been given some answers on Facebook!

The holes have a name: Tafoni.

Sandstone rock with empty tafoni, Edgewater beach, 2010

Tafoni (singular: tafone) are small cave-like features found in granular rock such as sandstone, granite, and sandy-limestone with rounded entrances and smooth concave walls, often connected, adjacent, and/or networked. They often occur in groups that can riddle a hillside, cliff, or other rock formation. They can be found in all climate types, but are most abundant in intertidal areas and semi-arid and arid deserts. (Wikipedia)

"Small cave-like features ..." And "often ... adjacent ..." That describes the ones I find on our beaches. Other sites mention that they can be large, even room-sized, but our shore tafoni are rarely much more than a couple of inches across.

Often the holes line up around the edge of a flat lump of sandstone. This one is on Stories Beach. (No, I didn't put the small stone on top; that's how I found it.)

But what causes these? How do they form, and why? Why in these positions?

Explanations of their formation include salt weathering, differential cementation, structural variation in permeability, wetting-drying, and freezing-thawing cycles, variability in lithology, case hardening and core softening, and/or micro-climate changes and variation (that is, moisture availability). (Wikipedia)

That's a partial answer, but seems to leave out any biological factors. So what about snails and limpets? And the anemones in the pits?

Tafoni full of tiny snails. Willow Point Beach.

Some researchers believe that, in addition to salt weathering, mollusks and other marine life may also initiate tafoni. They do this by creating small holes in the rocky coastlines, where they attach themselves and extract minerals. The hole grows larger over time until eventually the mollusk, or other organism, drops off. The hole is then left to the elements, like wind, rain, and tidal water. (WorldAtlas)

"Salt weathering". What is that?

Mixing salt cations and water can produce a supersaturated solution. When this solution evaporates, salt crystals precipitate in pores spaces. The resulting crystalline solid precipitated between mineral grains can exert stress and readily cause mineral breakdown. (Tafoni.com Weathering)

Several sites explain this in simple terms. Salt weathering shows up on shore rocks periodically wetted with salt spray. In the intertidal zone, the rocks are underwater most of the time, but spend several hours in the open air daily. In the summer, they are exposed to warm sunlight, and dry out completely.

As the rock dries, the salt crystallizes. These salt crystals expand forcefully enough to create small cavities. In intertidal areas, the drying periods are shorter than on the upper shore, so intertidal tafoni tend to be small.

Thousands of tiny snails in tafoni, Willow Point Beach

So here's my idea, so far: the larger sandstone rocks standing above the intertidal floor dry out sooner, and spend more time out of water. This may be part of the reason for the arrangement of the tafoni. Here, salt crystals create small pits in the soft rock. Tiny snails find food in these holes, and dig them deeper; they have the grating radulas for this task. Limpets also bore into rock to create protected sleeping caves.

More weathering occurs. Wind, waves, crystalizing salt, and some chemical reactions depending on the material forming the rock, all may play their part.

And then along come the anemones. Do they enlarge the holes themselves, maybe by chemical means? Or do they just expand to fit the holes they find?

Anemones in sandstone pits, Edgewater beach, 2010

That still leaves the question of arrangement; why do the tafoni so often form along the rim of sandstone piles? Why do they sometimes cover the whole rock? Why do they often riddle one rock in a group and leave the rest free?

Rim tafoni.

The more I learn, the more questions I have.

Such fun!

(The site, Tafoni.com, has much more information, under many headings. Start with Tafoni.com/Definition and go to -Locations to see tafoni on Mars.)

Rock houses

Anemones are squishy. Touch one (not the tentacles; sometimes they sting). Touch the stalk; it feels like watery Jello. It leaks tears at your touch, and shrinks. Now it's regular Jello texture, still springy, still soft.

They have no teeth, no rasping mechanisms, no scratchy outer shell. So how do they excavate holes in rock?

Sandstone boulder, Willow Point. With ancient anemone homes around the edge.

Another boulder, another set of holes. This is rock, not sand.

Sometimes the holes line up along the edge of a flat rock. Sometimes the whole rock is pock-marked. And the next rock, of the same material, is smooth, without a hole to be seen.

Some holes are just that; old holes. I poke at them with a finger. There's nothing there but rock, hard and dry.

Some holes are occupied. The surrounding rock is hard, but if I touch the centre of a hole, it shrinks away from my finger, leaking tears, exposing a flash of yellow or green jelly.

Anemones in their rocky holes, unhappy because I poked them.

The beach life is layered.  Here, crabs, limpets, and snails in shallow pools, a seaweed level (sea cauliflower and red algae), barnacles on the bottom of a flat rock, and a rim of holes around the upper side. And more barnacles and algae on the top. Crouch and look up at the underside of the rock; there may be a starfish or three.

Why are the holes so often lined up along the edge of flat rocks? Could it be something to do with the currents bringing foods, the way the anemones in my aquarium congregate near the top of the tank, sometimes half out of the water? Do they line up because new babies move only a little way from their parent?

Why do they choose one rock, and not the next? Why is one rock smooth, its neighbour completely pock-marked, and the next one free of holes except for one edge?

Are some of those holes ancient limpet beds, hollowed out by years of tidewaters? Is there a way to tell the difference?

And in my tank, why do the few pink-tipped green anemones who choose to stay at the bottom park themselves mostly on oyster shells, almost never on stone?

I ask them, but they never answer.

Beach contrasts

Stories beach at low tide is a wide, sandy stretch, perfect for walking, making sand castles, sunbathing, watching the sky ...

Looking northwest, to the coast mountains.

But this afternoon, I turned south, to the seaweedy, slippery, treacherous rocks. That's where the critters live.

Long dikes mini-hogbacks* of sculpted sandstone, interspersed with fields of melon-sized rocks.

Correction sent to me via Messenger from a geologist friend:

Geologically, the sandstone ledges are strata, not dikes, which would crosscut the layers (by definition), and are usually igneous. Because the sandstone layers are at an angle, they could be called mini-hogbacks or cuestas.

Thanks, Jenny!

That green sea lettuce is slippery. I fell once, in spite of extreme caution. But every stone hides a new community.

Sometimes the rocks seem to have been tossed randomly on a flat sandstone table. By giants.

The sandstone mini-hogbacks hold tidepools well above the low tide level. And there are fish in the pools.

Just out of reach, two harlequin duck couples stand watching me.

And yes, there were critters, new and old. And a few mysteries. That's for tomorrow.

A Skywatch post.

Pioneer

On sandstone exposed when the river goes dry, underwater come the fall rains, a bluebell plant homesteads in a sheltered corner, digging its taproot deep into the stone.

Common harebells, in the Oyster River bed.

Oyster River sandstone beds.

Valley of invisible birds

I was looking for birds, without much luck. I could hear them, even driving if the windows were open. A woman on the road had pointed out a couple of good birding sites; there were tanagers and goldfinches, she said. I saw nothing but flashes of yellow, rustling leaves.

A swatch of once-cleared land for the power lines looked like a good bet. I parked and hiked down the hill.

Birds gossiped and called all around me. None were visible. But ...

Deer in power line valley.

A well-travelled trail led off the main route into deep shade. I followed that, then another trail, this one barely visible, branching off down the hill. And came out onto the shores of the Oyster River.

Sandstone and shallow water.

I stopped at Woodhus Creek, which enters the Oyster a short distance upriver from this point, in the early spring. The water was up to the top of the banks, racing and tumbling down, roaring. The sound was deafening.

This week, the banks are dry, although the creek is still too deep to cross dry-shod. The Oyster River is wider and deeper, but shows the same pattern; sandstone banks, swept clean by the winter surge, smooth and dry under the summer sun.

The current is still strong enough for a good tumbling wave or two.

Sandstone rocks, carved and polished by water power.

More bird-free birding pics, tomorrow.

Cave dwellers

The morning brought a faint hint of sunshine, a promise of more. I loaded the camera, grabbed my coat, and hit the road. By the time I'd run a couple of errands, it was raining, but not too hard. I drove down to the shore to look at the water from the shelter of the car.

The waves were high and pounding in; as soon as I parked, I could hear them roaring. Rain or no rain, I had to be on the beach.

Waves, and a duck, resting calmly in the trough..

The tide was out farther than I've seen it so far this fall and winter. I went down to the water's edge, turned over a few rocks: crabs, crabs, crabs, and tiny barnacles.

Barnacles on the bottom of a rock. One limpet, one mussel. The crabs all ran for cover.

Sandpiper, just out of reach of the waves.

It was raining a bit harder now, but off in the distance, I could see the strange sandstone formations we had explored in bygone summers. I sheltered the camera under my coat and went to look at them.

Round rocks, and a dark row of flat sandstone, on a dark, rainy day.

This part of the beach has a solid underpinning, not sand, but flattish sandstone, with occasional "tables" fringed with seaweeds, rimmed and topped with small round indentations, up to about an inch in diameter. In between the sandstone tables, smallish, round stones  cover most of the lower slab. Large rocks are scattered randomly across the whole area. An unusual mix.

Sample arrangement.

This one got tipped on an angle. How, I don't know; it's heavy.

Holes around the rim of two tables. They remind me of cave dwellings I have seen on a Mexican mountainside.

When we investigated rocks like these a few summers ago, most of the pits were occupied by small, green anemones. I couldn't see any now, in the winter; instead, small periwinkle snails are hiding there. Maybe the anemones are underneath them, waiting for warmer weather.

Barnacles out in the open, snails in the tubs.

Anemones in sandstone pits, summer of 2010.

The rain picked up, and my camera was getting wet. I clutched it under my coat and hurried back to shore. I'll be back, next sunny day at low tide.