24 May 2016

Rockpool residents; chitons, a poychaete and a hermit crab.

A trip to the beach with the youngest field assistant on a warm day; the tide was out and there were plenty of rockpools to explore on the sideritic bench between Runswick and Kettleness. The rockpools were warm; a tribute to the evolutionary fitness of the creatures that live there. They've become adapted to withstand wide ranges of salinity, temperature and dissolved oxygen levels. The youngest field assistant was bossing the sampling show:


We found a pair of chitons, one rather plain the other a crazy pink:
Does it become pink through grazing on the encrusting pink algae thereabouts or has the algae decided to use the carapace of this rather slow moving shellfish as a home?

We also found a polychaete worm. S/he had an impressive little tuft of antennae on the head.

Being in a bit of an interested-in-shellfish phase right now I took a pic of this one happily hunkered down surrounded by coraline and red algae:

It promptly sprouted legs, antennae and eyes, and marched off, a bit of 'no pictures!' in its hermit crabby manner.

An upended rock revealed an anemone amid a colony of Pomatoceras worms with some green seaweed (Ulva lactuca) trying to get established.

 The youngest field assistant wanted to poke his finger into the anemone's mouth. The rock was replaced, the anemone unpoked after a quick lesson about nematocysts.

19 May 2016

The evolution of Runswick's Mesozoic marine reptiles.

The mudstones and shales which make up the lower Jurassic portion of Runswick Bay's pre-history are the fossilized seabeds from a time when Runswick was under a shallow, warm equatorial sea. Fossil finds hereabouts show that the sea was heaving with ammonites and belemnites, the muddy seabed was a mass of shellfish; Gryphaea (oysters), Pecten (similar to scallops), Pseudomytiloides (like a flattened mussel) and Dacromyia (like a small cockle) to mention but a few. The Jurassic seas were also home to big creatures too; plesiosaurs (think Nessie, only real), icthyosaurs (dolphin-alikes), crocodiles and turtles. Obviously these large, swimming creatures had an evolutionary backstory and here it is, free to read in an open access scientific journal:

Ecomorphological diversifications of Mesozoic marine reptiles: the roles of ecological opportunity and extinction
We haven't yet found a complete Jurassic marine reptile specimen which could add to the work done by Mr. Stubbs and Mr. Benton, but hope it's only a matter of time. Thanks to them, their publishers and the internet for letting those of us who are interested learn a bit more about this kind of stuff. (And I know the paper is about Jurassic marine reptiles per se, but I'm only interested in Runswick Bay. Dead reptiles in other parts of the world can find their own damn blogger.)

17 May 2016

Apologies for the radio silence...

going to the beach sampling, collecting and measuring is hard when you're coughing like a romantic poet dying of consumption. The lurgi (for amateur epidemiologists amongst my readers the local GP said that this winter flu epidemic came late and was an absolute stinker - the worst he had seen in his 25 years of doctoring) seems to have passed so I'll be back on the beach and posting regularly.

In the meantime do occupy yourself with some entertaining reading: the North York Moors National Park blog is a good read, they're up to G in their A to Z of the park so if you're interested in the Gardens, Geology and Goths of the Moors, pop over and have a look.

Capturing our coast is a wonderful initiative. If you haven't yet, go, read and if you can spare the time get involved in this wonderful citizen science project. We're an island and we should know and care more about our coasts and seas.

And if you haven't discovered it yet, off you go to Richard Carter's Nature Writing flipboard.

Until the new posts start flowing, have a whalestone, a concretion from the cliff about 1.5 metres across:

28 Apr 2016

The May Dalesman is out!

This month it's all about shellfish and Vikings, after a day sampling rockpools on Runswick beach with this blog's youngest field assistant. £2.99 from all places civilized.

19 Apr 2016

Finally, a spring day with some of nice fossils. (Updated)

We did a quick safari to the beach to find the almost up tide up (this pic is 2 hours before high water), so little natural history to be done. So we had to content ourselves with a very quick rampage amongst the rocks to see what fossils we could find.

As it happened, not a bad haul:
Right to left:
1. A 2cm diameter ammonite, juvenile or adolescent Arnioceras semicostatum (the specimens in the field guides, which I assume to be adult are 4 cm across). Andy from Andy's Fossils contacted me in comments to suggest that this is actually Hilderocas bifrons (likely to be found in Runswick) rather than Arnioceras which is not) for which many thanks. He's probably right.

2. At the bottom is a Gryphaea, a fossil oyster which died c. 185 million years ago. I and my field assistants find lots of these but this one is in a shingle-smoothed block of dead, fossilized, smashed together molluscs. Probably the result of a mudslide sweeping these creatures from their muddy home into an anoxic (oxygen-deprived) basin (I've been swotting up on the Jurassic conditions hereabouts, thank you Mr. - soon to be Dr. - I hope - Johnson) which killed them en-masse.

3. Coral or a sponge. Jurassic, much smoothed so hard to identify.

4. Star of the show. I think you're looking at a fragment of mid-Jurassic plant, probably a cycad. We found this on the beach at the foot of some cliffs where we know cycads have been found before. The place is a Site of Special Scientific Interest so off limits to fossil collecting but not off limits to 'measuring a section*', which is what my smart wife (a natural science graduate from the University of Toronto) suggested we do. You see, the rock matrix a round the fossils isn't what you'd expect on our beach. Up the cliff we went, looking at the changing geology as we did. After much scrambling, hanging onto blades of glass, scrabbling dirt away from the underlying rock we hit rock similar to that encasing our beach fossil. A glance at our geology field guides at home and it was bang in the geological horizon for the Jurassic cycads.

* Measuring a section means you find a specimen at the foot of a cliff (or, if you're unlucky, mountain) and traipse up the thing looking at every stratum to see where the thing came from.

30 Mar 2016

Upper beach seaweed, early spring.

Green Ascophyllum nodosum (knotted wrack) in full reproductive swing; the spotted lighter sacs are the conceptacles, the seaweed's reproductive organs. The wispy red algae is Polysiphonia lanosa which lives as a hemiparasite on the Ascophyllum. 
 

The Bay yesterday was looking rather splendid:


It was an Easter holiday ramble of the beach with the youngest field assistant, but we found a couple of Gryphaea, extinct Jurassic oysters:
The right hand specimen has a small, almost complete Gryphaea on the left hand side, the rest is made up of smaller specimens. I've been reading a dissertation of the Jurassic geology of this area which talks about anoxic events; periods when the seabed became inundated with dexoygenated water, killing whatever creatures got in its way. When you see large numbers of fossils dead together, an influx of anoxic water or getting caught up in a mudslide might be the cause. Some Jurassic creatures found as fossils in Runswick beach thrived in low-oxygen conditions such as these Pseudomytilus dubius, bivalve molluscs. These ones are rather splendidly pyritized (coated in fool's gold) on the outside of a pyritic nodule.


17 Mar 2016

Runswick Bay sand through the microscope.

The blue is (I suspect) a microscopic piece of slag from the ironworks that was built on Lingrow undercliff to the north of the village in 1857, and collapsed in a cliff-fall a year later. Or it could be a fragment of a mussel (Mytilus edulis) shell.


9 Mar 2016

A chiton.

These molluscs are unusual in that instead of having one big shell (like limpets or whelks) their armour is made up of eight overlapping plates. Under this exciting exterior is the creature's greenstuff; mouth at the front, algae-scraping radula to drag food into the oesophagus, a stomach and a coiled bowel that makes and excretes pellets of digested algal biofilm residue. There are gills down each side, under the shells. One group is carnivorous, trapping prey under its shell before consuming it.

Someone, a scientist of heroic patience, has suggested that like limpets, chitons have a homing instinct. Their sensory organs protrude between the plates of the shell to tell the chiton (of which there are an estimated 750 living species) what is happening and are wonderfully named: aesthetes.

Chitons are mollucs, class polyplacophora. For a brief and intelligent introduction to these creatures, the UCMP page cannot be beaten.

8 Mar 2016

A quick beach walk for Fossil Friday on twitter.

With lots of people tweeting their favourite fossils last Friday I thought I'd do a quick beach walk and photograph everything I saw. The tide gave me 35 minutes. Here's what the mudstone cliffs gave me. First Runswick Bay when I started:
 
The first thing I saw was a heavily wrecked ammonite fragment.
That's better. Arnioceras semicostatum I think. 
Back to much-mangled ammonites.

A belemnite guard, end on (or transverse section, as they say in scientific circles).

 Hard to ID bivalve counterpart (centre left) maybe Pseudopecten equivalvis and three Nuculana ovum.

A couple of Dactyloceras commune. No fossil walk near Whitby would be complete without a Dact or two. 


No idea. All suggestions welcome.
 
Pleuromya, three Nuculana and a fragment of a belemnite guard.

Fragment of ammonite counterpart.

Very weathered ammonite, not much to identify it from but I'm having a stab at Oxynoticeras oxynotum.

Small, smashed and pyritized Pseudomytiloides.

An ammonite in a nodule.

Another ammonite in a nodule.

More ammonites; part and weathered counterpart.

Not another ammonite!

Four more bivalves.

And just when you thought you were done with ammonites, I found a fossil collector's midden. These guys didn't make someone's cut.

The tide was flooding fast, the Bay had clouded over by the time I left.

1 Mar 2016

The March Dalesman is out!

Stop what you are doing and go to the shop, for the God's own goodness that is the March Dalesman is making the shelves a better place. The Yorkshire Coast has got a little smaller of late with a substantial cliff collapse at Port Mulgrave, so my column is mostly about landslips this month.
It's got lots of good stuff; daffodils at Farndale, Spurn Point, Ian McMilllan's poetic lessons for life (don't go to bed in your flat cap) and a look at Yorkshire's spa towns. The best £2.99 you'll spend until the April Dalesman.

4 Feb 2016

Pleuroceras are Yorkshire's under-appreciated ammonites.

Fortunately Andy has done a lot of hard work about this wide-ribbed ammonite. His blog is a must read.

Now I have an an excuse to re-repost my favourite bit of Runswick beach: a Pleuroceras counterpart colonized by barnacles. This specimen was preserved in the siderite section of Runswick beach; the hard, red expanse of stone exposed at low tide about halfway between Runswick and Kettleness.

26 Jan 2016

One of the most scientifically accurate restorations of an ammonite ever undertaken.

This ammonite fragment is one of the biggest in my collection; it's heavily worn after being tumbled around in shingle so it's hard to decide whether it's a Hilderocas bifrons or Arnioceras semicostatum.

Since it was blowing a 60mph gale, I decided that today would be a good day to take it to the beach with a pencil. And an 8 inch adjustable spanner for scale. The tape measure would have blown away, you see.


My very rough primary-school standard drawing around things suggests that the ammonite was 7-8 inches (14-16 cm) across. If there are fragments on the beach, there should be whole specimens in the cliffs waiting to be found.

If it's Arnioceras it's Lower Liassic, Sinemurian, Semicostatum zone.
If it's Hildoceras it's Upper Liassic, Toarcian, Bifrons zone.

13 Jan 2016

Port Mulgrave cliff fall: rotational slide (updated)..

Port Mulgrave is two miles north of Runswick Bay. A week ago the large portion of undercliff in the middle of the picture was at the top of the cliff. A few days ago, the rain-sodden clifftop (it has rained here for the last month) parted company from its parent Yorkshire and slumped down to the beach. Such a collapse is called rotational slip or rotational slide. The cliffs there are 320 (ish) feet and it looks like the clifftop has dropped around half of that. This pic was taken with a telephoto lens which compresses the perspective, so I suspect the slip is 2-300 feet across and the same from from sea to shore. I'll toddle over there on Monday with wellies, a spade, a rock hammer and my GPS and let you all know how big an event this was. And what fossils are to be found. I'll post a 'before' pic tomorrow.

Thursday; heavy rain and northerly gales forecast all day. Just the conditions that caused this slip in the first place. 


11 Jan 2016

So what did belemnites look like, and how did they live? (Updated)

If you visit the rocky ledges below Runswick village the shale flats towards Kettleness you will see the remains of belemnites, bullet-shaped fossils that look like this:


(Not sure what the little pyritic explosions at either end are, any suggestions welcome.)

But if you're rummaging among the shingle for fossils you are likely to see this kind of thing:

They're cylindrical bits of smashed up belemnite rostrum, the pointed specimen is a whole (but heavily abraded by being tumbled in shingle) rostrum. The rostrum was basically the belemnites's tailbone to which its fins attached. What belemnites looked like and how they lived was a matter of debate between pelaeobiologists because most of their living bodies were soft tissue that is preserved in fossil form rarely and then usually poorly.

However, if you're curious to see what enclosed these fossil cylinders and bullets in the Jurassic seas of Yorkshire (and elsewhere) go and read Adaptations to squid-style high-speed swimming in Jurassic belemnitids from the January issue of the Royal Society's Biology Letters. The paper analyses specimens where belemnite soft tissue had been fossilised and concludes that they were fast-swimming creatures that lived in the water column, rather than grovelling around on the Jurassic seabed.

Update: And thanks to Brooke Johnson for this: Last Suppers: Calamari del Mesozoico. More excellent stuff about belemnite soft tissue preservation and lots of good stuff about food chains and predation in Jurassic seas, which is just what Runswick Bay was 190 million years ago.

31 Dec 2015

Th January Dalesman is out!

My Yorkshire coast column goes historical. Robert Moorsom of Whitby commanded HMS Revenge, a 74 gun line of battle ship at Trafalgar. £2.99 at all self-respecting newsagents.

22 Dec 2015

A piddock shell (and King George V).

There have been a couple of days of gales, and the strandline was littered with shells including this half of a piddock:
The right hand side looks like a vanilla bivalve shell, the left is heavily distorted from the effort of grinding its way into shale to make a burrow. In many years of watching this beach I have never seen a live piddock; they obviously can't survive in an intertidal zone so well patrolled by gulls and oystercatchers. Their burrows show up in witchstones; pieces of shale with holes which were once piddock burrows which have been washed ashore. Local legend has it that if you nail one of these above your stable door it will ward off any witches that may try to steal your horse.
A piddock-bored witchstone, with Enteromorpha seaweed, a scattering of small barnacles, some encrusting red algae and a whelk.

I wondered if piddocks had any chemical help to bore into the rock but @RudkinDave said not, although other families of boring molluscs do secrete acids to help their digging. Having dug its burrow the piddock hunkers down, expends its syphon into the water and lives for around eight years. 

7 Dec 2015

Runswick Bay c. 1900


Many thanks to former Runswick resident Alex McCallum for this find of Runswick at the start of the last century. There is a post on belemnites and their living squid relatives coming up, but for now, enjoy Runswick of old.

1 Dec 2015

26 Nov 2015

'There's no fossils here,' said a visitor

stepping right over a Gryphaea...

And here, a bit over-exposed (sorry) is the rest of the day's Jurassica; two bivalves, three Gryphaea enclosed by ammonite fragment brackets with Laminaria saccharina garnish.