Rocks, ripples and reformers

There can’t be another short walk in the country where you can search out the fossil plants and animals from hundreds of millions of years ago including the oldest recorded amphibian footprints, walk across evidence of ancient earthquakes, touch rocks that were once 1200° molten magma and see the debris left by the last ice sheet to cover England, stroll past the site of a 10,000 year old Stone Age house, search out the tree stumps of a drowned forest where those Mesolithic people hunted, gaze at reefs that wrecked over 20 ships, look enviably of the bathing house built by a Prime Minister who invented a different cup of tea, smell kippers been smoked and all the time be surrounded by amazing wildlife. 

Transcript

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Series 6, Episode 2, Rocks, Ripples, and Reformers. This really is a spellbinding part of the Northumberland coast. It makes for a classic walk on so many levels. There can't be another short walk in the country where you can search out the fossil plants and animals from hundreds of millions of years ago, including the oldest amphibian footprints, walk across evidence of ancient earthquakes, touch rocks that were once twelve hundred degree molten magma, and see the debris left by the last ice sheet to cover England. You can stroll past the site of a ten thousand year old Stone Age house, search out the tree stumps of a drowned forest where those Mesolithic people hunted, gaze at reefs that wrecked over twenty ships, look enviably at the bathing house built by a prime minister who invented a different cup of tea, even smell kippers being smoked, and all the time be surrounded by amazing wildlife. It's only three miles one way along the coastal path, but will drop onto the rocky foreshore frequently, so if the weather is kind, this walk could take all day. We will be skipping backwards and forwards in time from over three hundred and thirty million years ago to the present, and, as ever, if you do this seaside walk for real, please be aware of the tides and that the rocks are pretty slippy. That was an introduction to a YouTube video of a walk I produced exactly six years ago this month. It was part of a short series of videos that started because we were all locked down for the COVID pandemic in 2020. Back then, I thought that as people were seriously restricted in what they could do outside, they might appreciate a virtual walk and find out just a little of what exists behind Northumberland's beautiful coastal scenery. In a couple of weeks I'm taking Ponteeland Wildlife Group on the walk for real. So I thought I'd add this story to the podcast series too. If you can, I hope you might take the walk. It is part of the Northumberland Coast Path, which is now part of the King Charles England Coast Path 2. It starts in Craster and ends in Sugarsands Bay east of Longhouten. If you'd like to read a more detailed geological guide, just try Googling BGS Howick Shore Excursion. We start in the car park at Craster. It's in an old windsill dolerite quarry. You get to see the rock close up. It looks like a hard rock, and it is. It was used for roadstone and bigger pieces for coastal defences. Two hundred and ninety five million years ago it was a molten rock, but not one that erupted from a volcano onto the Earth's surface. This one is an intrusion. It was injected horizontally between older sedimentary rocks. You can see the characteristic vertical joints and rough columns caused by its shrinking and cracking as it cooled. There's not much covering the windsill as we head to Cullenose Point, just thin soil, and you can see the rock exposed on the foreshore. At Cullino's, those same windsill vertical columns and joints are really obvious again, as is the noise and the white guano of the nesting sea birds that make it home. In the bay south of Culinose Point, the rocks are, with one prominent exception, sedimentary, and they show us too evidence of how dynamic the earth is. The limestone rock, complete with fossils of ancient sea life, crinoids, brachiopods and corals, has been bent into rolling waves. This layer of limestone is called the sandbank's limestone. In the sandstone and siltstone rocks that accompany it in the bay, you might see what look like strings of beads. They are the fossilized pellets of a burrowing animal with a tongue twisting name. Epione Milliform, well I hope I pronounced that right. Nearby is the exceptional rock, a dark one meter vertical blade that runs northeast across the foreshore. This was once a blade of molten magma, and it's associated with the injection of the windsill. We are walking across sedimentary rocks for the rest of our hike. Geologists like me who study rocks in intricate detail have names for each limestone and coal. But it's probably easiest if you want to get your head round these rocks, if we just think of them as many repeating cycles. Limestone covered by shale, then by sandstone and coal. Each of these rocks used to be sediments and plants and animals in changing environments. There were seas followed by lagoons, then rivers, then swamps, and the sea level rose and fell in response to the earth's ice caps shrinking and expanding. A bit further south where the coast and the road come together, you can access the foreshore again. Clamber down a grassy bank onto the foreshore and turn south, and you will soon cross the Howick Fault. If you look back in the cliff you'll see this fracture. The earth once dropped two hundred vertical meters on the south side here. Elsewhere you'll see the white calcite filled cracks in the rock. They look like rips in silk. They are caused by the tension in the earth pulling the rocks apart. More evidence of the enormous forces of nature in this little bay. At the south end of the bay, where the cliff turns east, you are at the spot where the footprints and underbodied trace of a three meter plus amphibian were left as it crawled out of the shallow water onto a muddy sandbank three hundred million years ago. These are some of the oldest footprints in Britain. I wish you luck in finding them. I've been back three times, and I'm not sure I can see them. Just north of Seahouse's farm is the bathing house, truly a candidate for the most desirable holiday let on the North Sea coast. It jumps us forward in time again to the eighteen thirties. Complete with its rock cut pools, it was built by the second Earl Grey for his fifteen children. Earl Grey, the same man who sits on the monument in Newcastle, was a British Prime Minister. He introduced the Reform Act to extend the vote and also oversaw the abolition of slavery. He is said to be responsible for the eponymous cup of tea, Earl Grey, for I'm going to claim a stake in that work for geology, because it was the excessive liminess of the local Howick water that caused him to add bergamot. At Rumbling Kern, named because the sea makes the sound of a churning barrel as it rolls in, there are dramatic lines and laminations in the sandstone. They tell us that this was once a channel of a fast flowing river. At the northern end of the haven is a detached stack of sandstone, capped with clay, sand and cobbles, testifying to the erosion and debris from the last ice sheet fifteen thousand years ago. If you look seaward across the haven at low tide, there's a rusty cube on the edge of the rocky reef. It's the boiler of the French trawler Tradorn, wrecked in 1930. Sadly five of its crew of thirty were drowned. Jumping backwards in time now to only ten thousand years ago, beside the cliff top path before Howickburn, archaeologists found flint tools, and then excavated a Stone Age house, one of the oldest and best preserved Mesolithic sites in Britain, and home to a coastal sea going and sea leeting community. But long before these people there were hunter-gatherers. They occupied the forests that are now submerged beneath the North Sea. There were woodlands and glades. Traces of these appear frequently, as stumps and roots, as the sea scours beaches along this northeast coastline. The cliff at Syogasands Bay gives us a wonderful view of the repeating layers of Carboniferous strata, and on the rocky foreshore you can find the fossils and imprints of these 330 million year old plants and animals. We may have focused on the times past, but as we've walked you can't help be thrilled by the natural diversity of our coast. The Kitty Wakes and Fulmas, oyster catchers and eiderducts, limpets and anemones, blackthorn and buckthorn, butterflies and wildflowers all beside the path. And in the midst of it all is a connection to that distant past, a living fossil, the horsetail fern. Except that three hundred and thirty million years ago it grew to twenty meters high. There is a wonderful symmetry of time and place and process here on the foreshore. Modern ripples left in the sand by a receding tide, and on the same beach, fossilized ripples in sandstone left by flowing water over three hundred and thirty million years before. In these simple scenes is one of the most fundamental principles of geology. If you want to understand the past, look at the present, and if you want to understand the future of our earth, look at its past.