7 Apr 2014

Fucus serratus with, er, feathers.

I didn't have my magnifier with me so these are either the 'soft silken hairs' that (according to my guides to the sea shore) cover infertile fronds of saw-wrack, or they are Spirorbis worms that have attached themselves to the seaweed frond but haven't yet secreted their shell.

The Bay today.

No filter, no Photoshop.

1 Apr 2014

Polyhalite...

More minerals from 1350 metres under Runswick. This time the great green hope of the potash mining industry hereabouts, polyhalite (a mixture of potassium, magnesium and calcium sulphates from the Permian period 260 million years ago). This is the stuff that caused great excitement with its discovery a few years ago, and the substance that Sirius Minerals, trading as York Potash hopes will make the proposed mine on the North Yorkshire Moors outside Whitby economically viable.

Left, polyhalite, right its commercial little brother common rock salt.


16 Mar 2014

The bay yesterday (view and the fossil haul).

Number One Field Assistant and I went on a fossil hunt yesterday and spent a pleasant hour rummaging through the wave-tumbled rocks and shingle at the foot of the mudstone cliffs. The winter has been stormy and a lot of shale has come down. Our friends over at Yorkshire Coast Trading patrol these beaches regularly and scoop up the nodules with pristine, iconic Dactyloceras ammonites inside, while we like what's left. Below, the day's haul. Belemnite fragments, a lone bivalve, ammonite fragments, a weathered ammonite counterpart, a stray piece of something like quartz and a few whole(ish) ammonites partially encased by hardened shale.

 
Below, the North Sea from Runswick Bay, yesterday evening. No photoshopping.



12 Mar 2014

Now this is what I call an erratic...

Runswick beach has its share of erratics - rocks dragged here by glaciers and dumped when they melted, like this piece of Shap granite. So it was interesting to find this in the boulder clay cliffs today...
Number One Field Assistant had at it with a rock hammer; out came an ammonite partially encased in a nodule. It's the first time in all my fossiling life here I've recovered a fossil from the boulder clay. It was a few hundred metres from where I found it to the nearest shale cliffs, and the closest are very fossil-light. I've never found an ammonite this good in them. Assuming it wasn't stuffed into the boulder clay to fool the unwary, I wonder where this was picked up by either the glacier or the boulder-clay. More Jurassic rock must underly the boulder clay, so maybe it was popped out of that as the glacier or clay ground on its way.

4 Mar 2014

A paddle worm (I think).

The youngest field assistant, being only 3, is not best left to his own devices on a rocky, sea-weedy beach with a fast rising tide, so I didn't get much time to study this:

It might look like someone has sneezed on a plate of modern cuisine, but what I think we have between the two anemones is Phyllodoce sp. Given time, I'd have examined the creature with my magnifier to look for antennae, but the spring tide was coming in apace, so I returned the rock to the shaded, seaweedy overhang whence it came and we made our escape off the beach.

The Bay today.


3 Mar 2014

The first appearance of the mineral Volkovskite in the UK...

is here! (Treat with caution; I am no geologist, but the person who passed this sample on to me is a very highly paid mining consultant who had this pressed into his hand where it was discovered by a proper geologist.) It's the pink-ish fan-shaped crystal.


It's found in evaporites (rock salt, potash deposits etc.) and was first described in Kazakhstan in 1966. It's subsequently been found in Canada and Siberia, and now we may be able to add North Yorkshire to the list of Volkovskite finds, with this specimen mined about 1350 metres under Runswick. If so (with all the health warnings above), it's a bit of a first to be announced on this blog.

Volkovskite is transparent, vitreous, clear or pink, has a hardness of 2.5 on the mohr scale and was named after A. I. Volkovskaya, the Russian petrographer. All that clever stuff was lifted from mindat.org's page on Volkovskite. Any proper geologists out there, feel free to pitch in. I've been wrong about things in rocks before.

Update; apparently Volkovskite is an unwelcome find for those whose job is to process potash deposits because it clogs the pumps used in processing. The other recently found mineral boracite is a pest because it's hard.















13 Feb 2014

Mytilus edulis (the common mussel)

which is, it occurred to me this morning when I found this disarticulated mussel shell, not at all common on Runswick beach.
This one had become home to a colony of barnacles in life, and having cemented their heads to the mussel shell in better times, they are with it for the ride in death.  Mussels live on hard substrates (rocky shores, piers, wooden piles etc), clinging on with sticky byssus threads*. I have walked most of Runswick Bay from the splash zone to low water at spring tides and have not found a mussel colony  exposed at low tide. The Bay's rocky beaches are home to limpets, barnacles and dog whelks, with gibbula top shells in rockpools; but no mussels, even below the barnacle-dominated rocks where you'd expect to find mussels.

I wondered why; a quick (and lazy) Google scholar search suggested some answers: dog whelks, crabs and oystercatchers all eat mussels and there are plenty of all three on Runswick beach. Shore crabs (of which there are plenty in Runswick rockpools) are described as 'voracious' and 'rapacious pests' when it comes to mussels in one paper (The mechanics of predation by the shore crab Carcinus maenas on the edible mussel Mytilus edulis, R. W. Elner, Oecologia, 36, 333-344, 1978). Dog whelks go for young, thin-shelled mussels and flocks of oystercatchers patrol the receding tide.

Starfish also like wrenching open and eating mussels, although I've yet to properly look for starfish we have found a few dead ones. So mussel predators are present, as is a strong population of other shellfish competing for space on the available rock.All these may account for the absence of Runswick Bay mussels.

In summer, the field assistant and I will take a low-tide walk around Kettleness headland to see if there are any mussel beds to be seen there. Here's the inside of the shell covered in nacre, a form of calcium carbonate. The blue blob at the bottom right of the shell is the scar where the posterior adductor muscle which opens and closes the two shells attaches.
The paper I quoted from, now more than 30 years old, can be viewed in full if you pay the publishers £30.

* It turns out byssus threads, which are secreted by the mussel's foot, have more uses than simply gluing the beast to its chosen home. As a free swimming larva the young mussel throws out a byssus thread which acts to slow the larva's rate of sinking through the water. In established mussel colonies, byssus threads are also defence mechanisms; a rash marauding dog whelk might get snagged and immobilized by a byssus thread and, unable to maraud any further, starves to death.

10 Feb 2014

What lies beneath Runswick Bay? Sylvite...

It's not often you get your hands on something from 1350 metres underground, but a passing mining consultant recently pressed this into my hand. Sylvite, crystalline potassium chloride from nearby Boulby Mine, which produces potash and polyhalites. Not strictly from the beach but part of the geology underlying it.

28 Dec 2013

Segmented sessile lower Jurassic fossil (ID needed please...updated)

Alright, I'm stumped. (That's what you get when you lend your precious fossil field guides to a forgetful neighbour.) Our Boxing Day walk on Runswick beach turned up a some ammonites, a few bits of belemnites, a piece of jet and a couple of devil's toenails.And this, or rather these since it's obviously a colony of them:

Update; thanks to AndyS and Anon, it turns out they're geological artifacts not fossils. They are cone in cone structures, their origins a matter of debate. While not what I had hoped, finding them caused me (and Number One Field Assistant) some delight, I have learned something and will look at strange shapes in the rocks with a new, skeptical eye in future.



Any ideas, do leave a comment. And click over to Andy's Fossils. How have I not found this brilliant ammanoblog before? He's a proper collector who cracks open nodules and having found lovely fossils prepares them meticulously then writes about it all very well indeed. Go and see him. At once.

26 Dec 2013

Happy boxing day from Runswick Bay...

The Bay had its best weather on for our Boxing Day amble. It was a falling neap tide, a gentle breeze and enough sun to make the beach football followed by a little half-hearted naturalizing a t-shirt affair.

We went for a wander beyond the thatched cottage above, scrambling over the Ascophyllum nodosum-covered rock to to the foreshore, it's shale (where you can find heavily flattened ammonites and belemnite guards, some with pyritized phragmacones attached) which is pretty well covered in seaweed. The top of the beach has plenty of rock-fall from the cliffs and is a shell-strewn midden where seabirds eat whatever they have pecked of the rocks or dug up from the sand. Here's a venus shell, Venerupis rhomboides:


And some flotsam; a razor shell (Ensis arcuata, I think) and a piece of Fucus serratus which is home to a fine colony of Spirorbis borealis:


This limpet met its end long enough ago for a polychaete bristle worm Pomatoceras triquiter to have taken up residence and built a home:


A calm Boxing Day view of Kettleness and Dabdike Rocks, knotted wrack on the surface buoyed up by its large air bladders.


Oh yes, and we found a few ammonites, a few devil's toenails and a block of hitherto unseen fossils, of which more in the next post.

8 Oct 2013

Jurassic bivalve CSI

Fossil bivalves (molluscs with two shells enclosing the soft bodyparts) are, as I said in the previous post, rare finds on Runswick beach. Here are three, left to right, Pleuromya, the subject of this post, the subject of the last post and, for comparison, the kind of fat little bivalve Dacromya that I find here only occasionally but are everywhere in the lower levels of Whitby's east cliff.


Something traumatic happened to the left hand Pleuromya: one shell has a clean hole punched into it...


On the other side the damage is even more extensive, the hole ragged:


This profile shot shows the damage to one of the shells; it was effectively caved in by whatever befell it:


In 35 years of searching these beaches I have never before seen anything like this. Bivalves worn smooth by being tumbled in shingle for years, yes. Bivalves heavily flattened by milennia of geological pressure, yes. Never, in the hundreds of specimens I've seen have I observed anything like this.

I'm inclined to rule out post-mortem geological damage. I'm not a Jurassic taphonomist, and if such an expert exists I'd be delighted to be contradicted here. Here's what I think happened to Bert (as I have come to call him. Or her.); minding its own business in the mud of a Jurassic seabed some 190 million years ago, Bert the Bivalve became a collateral snack for an icthyosaur (or maybe a plesiosaur). We know from the fossil record that icthyosaurs ate Jurassic shellfish, but I suspect it's unlikely that a small (Bert is 4 cm across) creature like this would be high on a large predator's prey list. Prey has to be worth a predator's time and effort to catch, eat and digest.

It may be that there is the fossil of a toothy marine predator that specialized in raking up molluscs from the Jurassic seabed just waiting to be found in these cliffs; but I think Bert was the accidental victim of a big, toothy predator snapping up something bigger and more worthwhile off the seabed.

In the attack, the sediment is stirred up, Bert is scooped into the icthy- or plesiosaur's jaws, and a second later he's in bivalvhalla as the jaws snap shut and a tooth punches through the tough aragonite of his previously trusty shell. The main meal is gulped down, a shake of the head (maybe Bert spent some time impaled on the fatal tooth, bugging the hell out of the predator) and Bert's remains tumble to the seabed. The benthic fauna clean out the organic remains from the punctured shell, the mud pours in and over the next 190 million years he's buried, fossilised, the rocks are transported by continental drift to 54 degrees North. One day his remains are washed out of a cliff to be found, mislaid round the house and found again.

Bitten Bert is not alone; our aimiable competitors over at Jurassic Trading have seen ammonites with clear bite marks out of them. The above is supposition, it might be complete rubbish. There could be a far more plausible explanation from finer minds than mine, but for now I'm happy to have in my collection what I think is the body in a Jurassic CSI.




30 Sep 2013

Jurassic bivalves.

These fossils are a relatively rare find at Runswick. Go a few miles along the coast to Whitby and the east cliff is full of fat little bivalves. Here they're bigger and rarer. To the left, a bivalve found loose and smoothed after a while being tumbled in shingle (it may be Pleuromya sp.), to the right a bivalve graveyard mostly composed of Cardinia  sp.


Below, hinge detail of the solitary (maybe) Pleuromya...


And here, the other side of the clump of Cardinia. They're much smashed up. Either they were damaged by geological activity after death and during fossilisation or they'd been eaten, churned up in the gut of a Jurassic marine reptile (icthyosaur or plesiosaur) and the indigestible shells excreted or vomited back in a marine midden. Robert Bakker makes a good case for land dinosaurs using gastric mills - eating stones to help the stomach grind up tough plant material as part of digestion - in The Dinosaur Heresies (a must for any dinosaur fan). Aragonite-covered shellfish would be even tougher dietary, er, nuts to crack. Any icthyosaur skeletons with stony stomach contents out there, I wonder? There are certainly icthyosaur fossils with ammonites where the digestive tract would have been in life.


More bivalves later. This time, I think, definitely a candidate for Jurassic CSI.

24 Jun 2013

Very low tide and a blenny.

I was expecting a low tide today (it's a spring tide, these fall two days after the full moon and two days after the dark of the moon) but not for the Bay to be almost empty of water...



It was a dog walk, not a naturalizing expedition, but the chance to explore rarely seen sandbanks and never before uncovered rocks was too much to resist. Plenty of new things to see, including this blenny, stranded under a rock by the receding tide:

Blennius pholis

Thinking it must be dead, I gave it a prod to better arrange it for a photo. To my surprise it flopped around, looking as indignant as a fish can. It had survived out of water in the moist atmosphere under the rock for at least an hour. I picked it up to put it in a nearby rockpool, but it wriggled from my hand, dropped to the rocky beach, stuck out a pair of long pelvic fins then half walked, half squirmed in a most missing-link-like way to the neaby rockpool and vanished happily into the sand. I think it's a common blenny, also called a shanny.

9 May 2013

A limpet.

Not just any limpet, but one that has found a safe little berth on Runswick beach:
This limpet (Patella sp.) has found a depression in a rock, has over many tides hunkered himself down and made a home. This individual has chosen a risky place to live: it is high on the beach and spends a lot of time exposed to the beaks of limpets' predators (seagulls etc.) as the tide falls. But no gull has managed to lever this shell off the rock.

30 Apr 2013

Jurassic mudstone cliffs, fossils, seaweed and...

These collapsing cliffs are the site of the old village of Runswick, which, in 1682, fell into the bay. You can see from the piles of loose fragments at the foot of the cliff that this an unstable place to be. Don't play here: bits of shale rain down constantly and every now and again a sandstone boulder (and the occasional village) falls onto the beach:
The loose rock at the foot of the cliffs can be a rich source of fossils but they aren't in great shape. I go there so you don't have to. Here's a belemnite guard:

 And a badly weathered and cracked Hilderocas ammonite:

Further away from the cliffs, entombed in the harder shale are many Inoceramus. Here's one well preserved occupant of the graveyard in the centre with a very weathered specimen to the left:

And away from the dead, the living. The green seaweed Enteromorpha sp., which I haven't seen on this part of the beach in 20 years:

Meanwhile, the faithful blogdog has something to add...
Fossils? Schmossils. I found a stick. Throw the stick!

22 Apr 2013

Cormorants on a distant rock.

Sounds like the first draft of a Ted Hughes poem, but no...
These splendidly named Phalacrocorax carbo were digesting on rocks exposed at low tide. The right hand bird was spreading its wings, which, it used to be thought, was to dry their feathers. Maybe so: they do spend a lot of time in the sea and diving to catch fish on the seabed, but the principal effect is that the bird's large flight muscles generate heat and help heat up the North Sea temperature fish in their stomachs to speed up digestion.

21 Apr 2013

A clifftop walk on a belated spring evening

While much of the magic here is on the beach with its fucus and fossils, every now and again the views and mammals get a look in. The blogdog and I went for a walk this sunset Sunday evening. The dog burst into a field and surprised a rabbit that hunkered down and waited for death:
 
As I was mulling over rabbit recipes, the dog instead noticed a stick and veered off, seizing the dead twig with idiot joy. Rabbit was off the menu:

Stick! Throw the stick!

The sun went down behind a distant hawthorn hedge...

Just throw the damn stick!

The near lunar lanscape of Kettleness glowed in the westering sun.

 Stuff the sunset! They happen every day. Throw the stick!

The moon was high, the sky blue, despite it being April the hawthorn wasn't yet in full leaf...

Who cares about the moon? Throw the damn stick! 

Somewhere on that ridge, around four thousand of years ago, a warrior was laid to rest in a long barrow. The barrow is long gone, ploughed out and reduced to a shadow in the soil visible only from the air.

Yeah, and in between warrioring he probably threw sticks for his dog, too.


I was half a second too slow to fully capture the pheasant that exploded from the grass:

THROW ME A GODDAMN STICK OR I'LL START DROWNING KITTENS! 

 And on the horizon, the setting sun caught the bridge of a ship in Tees Bay.

I give up. Look what you've done to me, I've started eating grass.