Sharks Tooth

Following on from that last post. This is what a good sized shark tooth looks like when recovered from the marine clay before in reaches the intertidal. 

Baby teeth

Fossils are continually eroding out of the ever seaward crawling cliff face, by the time they reach the intertidal virtually all of the fragile shells have fragmented and crumbled. Only the sharks teeth tend to survive. Although by the time you find them along the low tide line, unless you're very lucky, they're usually quite degraded. They've survived unscathed embedded in marine clays for 40 million years, though being rolled amongst the sand and pebbles for a few months soon wears them down...eventually to nothing. Still, even the degraded ones are cool, it's always nice to find something of that sort of age.

Stratigraphy

Walking through the northern reaches of Denny Lodge Enclosure I notice where one of the drainage ditches had recently been re-cut that the material piled on the banks was full of small shells and shell fragments.  These small shells and shell fragments were in grey blue clay, very similar to that which emerges in the cliffs at Barton, in fact they're the exact same Eocene sedimentary deposits. About 40 odd million years ago the whole region was an extensive shallow muddy lagoon/sea.  What struck me was the stratigraphy, or at least how close to the surface these ancient deposits were, the grey blue clay is not more that 30 cm from the surface, and I'm not sure that the orange clay horizon above it isn't just oxidized grey blue clay. The material heaped in the banks was absolutely stuffed with shell, the sea must have been chocker with life. The proximity of the clay to the surface, and that it extends under the whole forest and beyond, explain why the forest is so wet.You're not walking in the forest, you're really paddling in an ancient sea.

Home

It's taken time, 40 million years in fact, but this Eocene shell has made it home to the sea at last. To think this little shell last enjoyed bathing in a sun drenched sea 38 million years before our earliest earliest ancestors stood upright. Crazy. 

Eocene beach

I was walking in the Eocene this afternoon under the unseasonally warm sun, which reminded me that when these layers were laid down this area was a tropical lagoon. It's been a while since I'd walked these ancient horizons, and the landscape has changed noticeable. There are still land falls, slips and slides, and some are quite substantial, though for the most part the fluid landscape has been temporarily stabilized by colonizing plants and shrubs. Very successful colonizers are the Cat Tails, which now cover swathes of the wetter areas, Willow trees who I was surprised to see growing in quite some numbers, their canopies filled with bird song, and many of the areas which were exposed clays are now covered in a layer of tough grasses and horsetail. Still, there were enough exposed Eocene horizons to keep my eyes occupied. The entire surface of these exposed horizons is covered in shell fragments, as well as plenty of complete shells in various sizes and of various types, and the occasional sharks tooth. The 'Barton Beds' as they're called are well known in palaeontological circles, are an important research resource and some impressive specimens have been collected here. The best time for fossil hunting are over the coming months of bad weather, when land movement is common and virgin horizons exposed. Care needs to be taken as the area is dangerous and you can find yourself knee deep or even waist deep and in need of rescuing with one careless step; even today when the surface is still quite dry and stable, care was required. A great walk though, so much to see and think about.

Sharks Tooth

40 million years ago this sharks tooth was swimming around a vast lagoon, doing shark stuff. Since then it entered the geological matrix, ceaselessly moved through said matrix bound in a layer of compressed lagoon bed, then eroded from its ancient bed, it was carried by surface water until today this tiny 9mm tooth found it's way on to the beach and into my hand.  Time's some crazy shit.

Eroding coastline

The tide was coming in as I walked the foreshore below Barton Cliffs and the Barton beds, a rich source of fossils which extends well inland beneath the New Forest, occasionally showing in the banks and beds of the forests streams. Soon sea'll be lashing the soften clay and 40 million year old lagoon deposits, long aground will be returned to whence they originated. Above us the sky was grey, the wind roared, the sea was grey and all in all there was a foreboding atmosphere about the place this afternoon.  On a bright day, with a mill pond sea, it's easy to forget that the sea can be unforgiving; on a day like today it's easy to imagine. I didn't hang about.

Bindon Fossil Forest

Between Mupe Bay and Lulworth Cove is the Fossil Forest. Reached by a steep staircase, down which you descend through geological time, back to the Jurassic land surface of the Fossil Forest ledge. Don't be expecting to see fossilized trees though, that's not what the fossils represent. Rather what you see are the fossilized remains of the algae (through the millenia turned into thrombilites) which once grew around the bases of coniferous trees, probably akin to Cypresses. Like the geology at nearby Bacon hole the stratigraphy lays at 45 degrees from horizontal. Directly above the thrombilite level is a thick band of exposed Broken Beds which allows you to see just how fragile and jumbled these beds are. The pieces stone which form the main constituent of the broken beds appear to have been laid down in bands, and then these bands have been smashed to pieces and those pieces concreted back into bands. I don't know, I'm no geologist.  I do know though, that it's sites like this which make our Jurassic Coast so important.

Gad Cliff

The under cliff and shoreline below Gad Cliff have always held a certain allure and mystique for me. I've always wanted to explore them. Deep within the ranges and difficult to access, with signs telling you there is no access beyond this point, it's always appeared off limits. Years ago we were even hailed by a military helicopter and told to leave after passing the first Danger sign, admittedly the range was in use. I say in use, we didn't hear anything, but Monday to Friday afternoon the land within the range is closed to the public. Even if it were open, access around the shoreline from Kimmeridge is precarious, with the chance of being cut off by the tides in Brandy or Hobarrow Bays. You can get to the under cliff from the base of Tyneham Cap, but that too is precarious, this time due to a shifting land surface of Kimmeridge Clay.  So, we've never walked here. Today though that changed as I ventured around the coast, past the signs and into new territory. We'd gone as far as Brandy Bay before and up the slides to Tyneham Cap, but no further. I've decided to walk out along the beach and return along the higher under cliff. Care is required. The beach is strewn with rocks of all shapes and sizes set amongst the odd clay slide. There is no direct simple track, it's all climbing and jumping or more like scrambling and slipping. As I walk I look up and wonder at the new views, new perspectives. It feels so wild, so open and empty. I'm feeling naughty, a transgressor and wonder if my progress is being watched. It is, but not by people, as far as I'm aware anyway. Deer run in groups along their thin trails directly under the cliff up above me were the under cliff begins its sweep down towards the sea. More Sika Deer than I have ever seen in Purbeck, 50 plus. They watch me closely, I can't imagine they see many people, not along here. I don't see a single human foot print anywhere along the beach. I don't make it all the way to the end, about 2/3rds of the way along I turn back, saving the rest for another walk. I return along the under cliff. The under cliff is all rough grass and stumpy wind bent shrubs, with some bigger trees forming a wood at the Brandy bay end. The ground is soft in some places and covered in fissure in others. You could do an ankle if not careful. There are no paths beyond Deer trails on the under cliff; it's all hard going. But so beautiful, so wild. I stumble on through spiky shrub and razor sharp bramble. Occasionally I pause at a notable sized boulder to climb up and take a look about, before soldiering on towards the wood. Walking/climbing though the woodland above Brandy Bay, it's clear this is where the Deer hang out, the ground is churned by their hooves and you can smell them. Then, finally I emerge out of the slides at the base of Tyneham Cap. What a fantastic walk. Gad under cliff and beach were every bit as cool to explore as I though they'd be. I felt more in nature today than I can remember, and I always feel at one with nature. It just felt so wild, so untouched and so isolated. I didn't see a human foot print anywhere, not a one. There's still plenty to explore too, and I look forward to more walks here. Now though, the steep climb to Townley Shentons seat.

Barton Cliffs

All along the section of Barton which is exposed directly to the rasping sea the cliffs are slowly making their way back to the waters from whence they came. As well as the sea the recent rains cascade down the 40 million year old deposits, easily cutting channels through the sticky clay. In other places the water has mixed with the clay which now oozes like a lava flow towards the beach.  It's a good time for fossil hunting and the area is well known for its broad range of shells and sharks teeth, amongst other things.  The mud slip landscape can pose hazards at any time of the year, with people frequently requiring rescue from a dangerous situation, but the wet season is by far the most hazardous. Care should always been take. A few weeks back the cliffs were right angled to the beach, now they slump at the base with great heaps of oozed mud. Slumps in which one could easily loose a boot or find themselves stuck knee deep. I eye them with suspicion as the waves rolling in forced me closer to them. The tide is in and there is hardly any beach and in places none, making you to run, during the waves temporary retreated, to the next stretch of beach.  The sky is a beautiful blue today, a deep and intense blue. It's not completely empty, with decimated clouds above and more menacing formation on the horizons. This is an interlude, there have been a couple today between rain or hail episodes. Still, enjoying while it's here.