High Tide Blog
Roger’s blog appears regularly in the Scarborough Review. Read his archive of posts here.
The holiday season is upon us. For some it’s a time to relax but if you’re in the tourism business then summer means hard work. That’s not such a problem when work means more time out in the open air on the glorious Yorkshire coast. As soon as the Scottish schools broke up Hidden Horizons started their programme of fossil walks, rock-pooling, forest schools, astronomy and a host of other activities.
So last week I found myself at Cayton Bay with families from Kelso, Perth and Stirling all eager to find fossils. To be fair it didn’t look like a great evening out. When I left home at 5:30 pm there was a light drizzle which, by the time we met up at Cayton, had turned heavy and dreek. Undeterred we walked to the bay and – guess what – the rain stopped and, when we looked around, there was no-one else on the beach. A beautiful vast expanse of sand and pebbles all to ourselves – what a great feeling.
Once we got to work on a bank of pebbles we were soon finding fossil corals, crinoids and bivalves (ie mussel, clam and oyster shells). One fossil that’s often overlooked is the bullet-shaped belemnite. The fossil is the remains of the guard, the internal bony part of a squid-like animal. We found several at Cayton Bay. One in particular still had the phragmocone attached; this is the cone-shaped chamber at the blunt end of the bullet-shape. The creature lived within the phragmocone with its long tentacles extending outwards.
While they all have roughly the same form, belemnites come in a huge variety of sizes with slightly different shapes – long and thin, short and wide, slightly waisted, sharp ended and blunt ended. This matters hugely to specialists who use belemnites to age rocks, but for the beach walker it’s fun to spot the differences.
For information about summer fossil hunts visit: www.hiddenhorizons.co.uk
I’ve been out and about this month taking photos. While most people like to snap a good view or a nice sunset, with me it’s rocks. This can lead to some strange moments. A man walking his dog near Allerston stopped to watch me pointing my tripod and camera at a stone wall. ‘Grand day,’ he said, but he probably meant ‘What on earth are you doing?’
Last week there was a lovely forecast for the evening hours, so I set off for Sutton Bank with a boot full of camera, a banana for my tea, and a head full of optimism. Just past Helmsley a bank of grey cloud started to fill the western horizon. ‘Where’s that come from?’ I wondered and I wasn’t the only one. Several farmers were out turning an early hay cut, looking to the skies and scratching their heads.
Undeterred I ploughed on. I parked near a spot called Dialstone, loaded up and walked up to the Cleveland Way at Boltby. The sudden view across the Vale of York was spectacular. Here you’re standing on the top of the Middle Jurassic looking down to Triassic rocks on the valley floor 110 feet below. The escarpment below was gouged by massive ice sheets travelling south, gouging and ripping through the rocks and leaving a great inland cliff.
Unfortunately the bank of grey cloud was turning nasty – I watched the rain over Thirsk and cursed the BBC Weather website – the whole of England was supposed to be dry. I figured I had around half an hour. I turned north along the clifftop for a few hundred yards then ducked down into Boltby quarry, where layers of Middle Jurassic grit are exposed. I just had time to put up my tripod and get snapping when the first drops started to fall. I kept going until the lens started getting spotty, packed up and marched back towards the car. I soon discovered that the rain was being thrown horizontal by a strong wind; by the time I got back I was drenched.
Next day I downloaded the photos onto my computer expecting the worst, but surprise, surprise they were really rather lovely – if you like photos of wet rocks, which of course we all do.
Earlier this week I was wandering along a spot called Beadlam Rigg. There’s no reason why you should know it, but it’s another one of those breathtaking landscapes that decorate this part of the world. And, of course, it owes its beauty to the underlying geology.
A narrow road takes you three miles up a steady climb all the way from Beadlam village, just this side of Helmsley. The road winds through pasture and occasionally arable fields. This is the dip slope of the Tabular Hills, all Upper Jurassic rocks in layers of limestone and grit. The pastures are on the lime-based lower slopes. The road comes to an end, as all good things must, and then you walk up for a mile or so into a piece of forest. This forest runs all the way along the top of these hills, in a belt stretching from Scarborough to Helmsley. It is planted on a band of infertile rock known as the Lower Calcareous Grit (LCG). The forests are there because the grit isn’t good for crops or pasture – Broxa, Langdale, Wykeham, Dalby and Cropton Forests are all planted on the same layer of grit.
The hard grit forms a ridge on top of an escarpment that winds across the landscape like a drunken snake. The scarp here is called Rollgate Bank but the same slope has a hundred names, from Jacob’s Mount at Scarborough, to Crosscliff in Dalby Forest, Bluegate Hill at Gillamoor and Rievaulx Bank above Helmsley.
I walked through the belt of forest and there it was: a view north across Skiplam Moor towards Bransdale, east towards Rudland Rigg and Farndale and west to Helmsley Moor and Bilsdale. Standing on top of the Upper Jurassic ridge, peering down over the Middle Jurassic moors, I was looking back over 20 million years of earth history. Then quite suddenly the sun came out – and time stood still.
Why did the Holbeck Hotel slide into the sea? Why aren’t there any rivers flowing to the sea between the Esk and the Humber? And why are the pebbles on our beaches full of rocks from Scotland and Scandinavia? One answer will cover the lot – ice. From around 100,000 to just 11,500 years ago northern Europe was gripped by freezing weather; in the coldest periods temperatures were between –20 and –30 degrees C. With each drop in temperature, ice sheets spread southwards from Scandinavia, Scotland and the Pennines, carving their way across the North Sea and the lands of northern Europe.
Once temperatures began to rise around 11,500 years ago millions of tons of mud and rubble, dragged along by the ice sheets, were dumped across this region. The ice sheets and glacial lakes contained vast quantities of water all of which melted, and most of which now lay trapped by banks of mud and boulder clay. The mud still lies in a huge strip along the coast and in other low-lying areas. Look carefully at the cliffs at Sandsend, Saltwick, Cayton Bay and you’ll see how red mud fills in old river valleys.
The layer of mud on the cliff tops produces a fertile strip of land but it has its dangers. Water soaks into the mud and washes it downwards, or forms a lubricating layer which can sending it sliding over the underlying rock. The Holbeck Hotel and the Knipe Point bungalows are some of the victims of this movement but you can see its effects everywhere.
An ice sheet pushed in from the sea into the flat area of the Vale of Pickering. This left a bank of mud at the eastern end that blocked the River Derwent – the result was a shallow lake. Take the train from Malton to York and you’ll spot the steep valley at Kirkham Abbey where the Derwent broke out of its glacial lake. After rising just 5 miles from the coast it takes over 130 miles to reach the sea via the Ouse and the Humber.
The effects of the ice are everywhere from the Mere to Newtondale to villages like Robin Hood’s Bay and Staithes.