Fossil Sponge from Flamborough

This fossil sponge was collected from the beach at Selwicks Bay, Flamborough Head, on a Rockwatch weekend in the early 1990s.

It was embedded in a fragment of chalk that had fallen from the cliff, so it dates from the Upper Cretaceous Period, 95 to 65 million years ago. I drew it for my 1996 book Yorkshire Rock, A Journey Through Time but since then the chalk that surrounded it has split into shards. The collar of the smaller sponge has disintegrated too.

How I imagine it might have looked, growing in the chalky ooze of the Cretaceous sea bed.

Sponges were common as the age of the dinosaurs drew to a close. They had a sac-like body with a central cavity known as the cloaca.

The nearest species that I can find is Laosciada, a mushroom-shaped lithistid, a kind of demosponge, informally referred to as a calcisponge. It lived in deep water, between 100 and 400 metres.

The skeleton of the collar of this sponge is made up of interlocking spicules, which look like little pyramids in close-up. They’re made of silica which, remineralised, forms the layers of flint found in the chalk.

Devil’s Toenail

I can never resist picking up a Devil’s Toenail when I spot one on the beach and, although this one is more worn than others I’ve found, I decided to draw it and, in the process, have a change from my usual pen and watercolour approach. For the initial pencil drawing I used a Uniball Shalaku mechanical pencil with a 0.5 mm lead. No pencil sharpener required, just a touch on the side lever to advance the lead.

The Devil’s Toenail is a species of fossil oyster, Gryphea, a bivalve mollusc. Usually, as here, it is only the lower (anatomically the left) valve that is found. The smaller right valve was hinged to it like a lid.

Fossils of the Whitby Coast

I’ve got several field guides to fossils at home but I was still tempted by Fossils of the Whitby Coast, a photographic guide, by Dean R. Lomax because it’s so specific to this particular stretch of Jurassic coastline.

It includes more that two hundred photographs and illustrations, photography by Benjamin Hyde and illustrations by Nobumichi Tamura.

In most cases, colour isn’t necessary for the identification of a fossil, but it’s useful way to get familiar with the physical appearance of the odd fossil that you might spot amongst all those pebbles and shells on the beach.

Tamura’s illustrations intrigue me: the majority appear to be the digital equivalent of a watercolour illustration but a number have been created using a 3D modelling computer program.

Lomax and Tamura went on to produce Dinosaurs of the British Isles, hailed as ‘the single best reference on British dinosaurs that has ever been produced’.

Links

Fossils of the Whitby Coast by Dean R Lomax, published by the Siri Scientific Press

Dean Lomax, palaeontologist

Greenfield Valley

9 a.m.: The mist has cleared and we can see the conifer plantations of the Greenfield Valley again.

Fieldfares and starlings
Fieldfares and starlings

Two fieldfares settle on the rushy pasture in front of the farm. With their grey rump, greyish head and slithers of white on the front of their folded wings they’re more strikingly smart than the resident mistle thrush and the female blackbird which are also about this morning.

When one of them perches on the power line and starts preening, we see the dark band at the end of its tail and two tear-shaped streaks of chestnut on its breast.

Post Pecker

great-spotted woodpeckerA male great spotted woodpecker probes every crevice on the stout timber corner post of a wire fence. Having checked all around it, it perches on top then flies to the adjacent fence post. The slimmer post evidently doesn’t offer the same possibilities so it flies off, with bouncing flight, to the power line post and continues probing.

Two dippers are working their way down the beck towards Oughtershaw this morning; one wades in then completely submerges.

heronOn an afternoon walk to the Greenfield Valley we see a heron flying up Langstrothdale along Oughtershaw Beck, four pipits (no doubt meadow pipits) and a kestrel.

Zephrentis

ZephrentisPausing to take a closer look at some crushed limestone on a forestry track, I find this complete fossil of a funnel-shaped coral amongst the more common macaroni-like lithostrotion corals and the stout toadstool cap-shaped shells of brachiopods (which I’m assuming are Productus).

The funnel-shaped coral is Zephrentis phrygia, given its species name because of its resemblance to the Phrygian cap, a tall, pointed felt cap which was worn with the point tilting forwards.

Harebell, yarrow and herb robert, Oughtershaw.
Harebell, yarrow and herb robert, Oughtershaw.

Harebell, yarrow and herb robert are still in flower on the banking below the drystone wall on the road immediately to the south of Oughtershaw.

Carnosaur!

  • Dilophosaurus

When drawing dinosaurs, I get all the reference that I can find together and reconstruct the animal by drawing a rudimentary skeleton and working up a particular pose but wouldn’t it be great if I could set out with my sketchbook and draw the living breathing animal? That would probably be unwise when it comes to the carnosaurs but I had the chance to do the next best thing back in October 1997 when the Carnosaur! exhibition of animatronic dinosaurs was showing at the Yorkshire Museum.

  • Triceratops

Link: The Yorkshire Museum

Bilberry and Heather

heather and bilberrylichen covered rock11.20 a.m, mid-height stratus, cool breeze: I’m reminded of the piece of childhood writing that I re-read the other day (Blue Remembered Hills):

‘I found a dry bog plant and a stone with water trickling down the middle and green on the stone around it’

That was when I was aged nine and here I am, over half a century later, still fascinated by the plants and rocks of millstone grit moorland. No wonder I feel as if I’ve come back down to earth every time that we get out here.

I add colour using watercolour pencils but, once again, I’ve forgotten to bring my water-brush so I dab it with a finger moistened in a puddle on the moorland track.

club moss fossilGiant Club Moss Fossil

I draw the club moss fossil in the comfort of the Bank View Cafe at the end of the walk. I’ve spotted a few impressions of Carboniferous plants in the millstone grit blocks that make up some stretches of the path at Langsett and someone has brought together a small selection of plant fossils on the windowsill in the cafe. Shouldn’t every cafe should have a collection of local fossils, rocks and minerals?

Orthoceras

orthoceras

This belemnite-like cephalopod was actually more closely related to the present-day Nautilus. This fossil from Morocco has been polished to show the compartments that the cone-shells were divided into. Each compartment or camera is divided from the next by a wall or septa but connected by a central tube called a siphuncle.
After the death of the occupant the compartments filled with gases as the soft parts decayed and, in some cases, kept the shells afloat. Fossils show that they would drift along broad end first, sometimes trailing the pointed end along the sea bed.
Just as cockle shells tend to get concentrated in a particular part of a sandy beach, orthoceras shells are sometimes found sifted into such concentrations that the fossils are called ‘Othoceras’ limestones.
Orthoceras was a predator and scavenger of the Ordovician and Silurian, 400 to 500 million years ago. It swam with it shell horizontal in the water.

Blackthorn Blossom

Coxley Wood

It’s been a good year for blossom. The splash of blackthorn at the edge of the wood has lasted well and is still looking at its best.

Most daffodils are looking seedy, crocuses have vanished and as I write this I’m looking out over weedy veg beds that are crying out to be planted.

It’s National Gardening Week here and we’ve got a long Easter weekend ahead so I better get started.

Parking Lot Fossils

fossilsI decided to go for pencil and wash for this illustration for a forthcoming Dalesman article. HB pencil seemed more appropriate for grey forms and I thought that pen and ink might flatten the forms.

I picked these up at Nethergill Farm, Langstrathdale, last summer amongst the crushed limestone of the parking area. There are three fragments of sea-lily stem, a darker fragment run through with the fossil coral Lithostrotion and, at the back, a fragment of one of the valves of a fossil brachiopod.

They date from the Lower Carboniferous period, some 350 million years ago when a tropical sea covered the Yorkshire Dales.

Tree Ferns

I DREW this group of tree ferns from plants in the fern house at Kew Gardens. It was a frosty winter weekend and the prospect of drawing in the shelter of a glasshouse appealed to me. Unfortunately when I got there the fern houses were closed for maintenance, so I had to stand on the frozen turf outside and draw this tropical scene through the window.

This was back in the winter of 1976-77 and I was gathering visual reference for my first book, A Sketchbook of the Natural History of the Country Round Wakefield, for a fold-out diorama of the coal forests which covered much of Britain 300 million years ago. The giant club-mosses and giant horsetails are long gone but modern tree ferns are almost identical in appearance to the tree ferns and ‘seed ferns’ (an unrelated but very similar looking group of plants) that grew in these primeval forests.

I felt that drawing from real plants would give a touch of believability to the drawing, a kind of ‘everyday’ look which can be difficult to achieve when you’re reconstructing an exotic landscape.

Today, I’ve been revisiting that landscape, part of my past as well as part of the distant past of our planet, as I’ve been asked to prepare a coloured version (coloured in Photoshop that is) for an information board for a country park on the site of a former colliery. The stored energy in the coal comes from sunlight that fell on these long vanished forests 300 million years ago.

Crinoids

WHEN WE were walking between Hope and Castleton in the Peak District on Wednesday, we came across crinoid fossils in some of the capstones of the drystone wall as we crossed a stile. Crinoids are also known as sea-lilies although they’re invertebrate animals, relatives of sea urchins and starfish. They’ve been called ‘starfish on stems’; creatures that spread their arms to catch food particles.

They’re usually found where a current wafts across a reef. At the time these fossils formed what is now the Peak District lay close to the equator.

This comic strip version of how fossils form is from my 1991 geology A-level notes:

Graptolites

500 MILLION YEARS AGO: in the world’s oceans, graptolites, colonial creatures, float with the currents. They are too small for their accumulated remains to build up into sediments on the sea floor but, given enough time, they can leave a thin layer in the fossil record. This can happen only where sedimentation is slow, for instance hundreds of miles away from land.

Their fossils look like calligraphy, hence their name, taken from graptos, the Greek for ‘marked with letters’.

Life on the Reef

330 MILLION YEARS AGO Castleton: a reef built up by algae separates a calm shallow sea to the south from a sea at least 150 metres deep to the north. In contrast to the graptolites, which are heading for extinction at this time, some organisms are so successful that they form sedimentary rocks. These include in particular; crinoids, corals, bivalves and brachiopods.

In my A-level notes I’ve written; ‘Allochemical : stays in place’ but this is misleading: allochemicals are chemicals that come from elsewhere. ‘Allo’ is from the Greek for ‘other’ or ‘different’. In the case of the reefs at Castleton ‘allochemical’ might refer to the chalky ‘cement’ that holds the shell fragments together. The cement-like matrix may have come from elsewhere but shelly sediment itself is autochthonous, meaning that it is ‘not transported’ that it formed ‘in place’.

Stone-lilies 

‘. . . we find masses of limestone wholly composed of the stems of the stone-lilies, as they are rather poetically called. This stone is often seen polished in mantelpieces ; when exposed to the air, the softer parts, which are immediately between the stems, weather away, leaving the surface of the rock as if the fossils had been stuck on to it, as in the illustration of encrinitial limestone (Fig. 75). The heads of the animals which the stem supported were a corona of tentacules, with a mouth at the centre. These arm-like feelers waved about in the waters, bringing into their mouth the prey which they enclosed. As specimens, we give the Cyathocrinites planus (Fig. 76) and the Woodcrinus (Fig. 77).’

The Popular Educator, Volume. V, c. 1860?

Calamites

AS WE WALKED up to the moor at the top end of Langsett Reservoir I spotted this fossil of Calamites in the sandstone slab of the footpath.

Calamites was a the giant horsetail of the Carboniferous Period, 300 million years ago. Whorls of narrow leaves grew from each joint in the stem. In the close up you can see what appears to be a joint at the top of the picture.

Along with giant club-mosses, the horsetails of the lush tropical forests of the Carboniferous were fossilised to form coal seams. In West Yorkshire we still derive most of our electricity from coal-fired power stations so this entry in my online nature diary has, most likely, been powered in part by solar energy stored by these giant horsetails 300 million years ago.