From mountain peaks in sparkling sunshine, to rolling moors enveloped in a misty murk, Britain offers an unrivalled variety of landscapes and accompanying weather. This diverse scenery has been moulded over many millions of years by the various forces of nature and its creation is a compelling tale. In this feature, Kate Ravilious pokes around the nooks and crannies of the Yorkshire Dales and the Peak District to reveal an exotic and tumultuous history.

Malham Cove, Gordale Scar, Kilnsey Crag and Gaping Gill, just a few of the many spectacular places to visit in the Yorkshire Dales. Some of the hardest climbs, best pot-holing and scenic walking to be found. One hundred metres of naked limestone rear up in front of you at Malham; climb it if you dare. While Gaping Gill is a monster hole that is capable of swallowing York Minster. It is all awe inspiring scenery that owes its existence to a varied past.

The tale begins many aeons ago (350 million years to be precise), long before the first dinosaur set foot on land. Visiting the southern Pennines would have been a bit of a diving expedition but sunshine was guaranteed. Brightly coloured fish darted about in the tropical waters, while shrimp like creatures bobbed up and down. Large woodlice like creatures, called trilobites, crawled along the bottom amongst the sea lilies. Coral reef islands were scattered around and it looked quite similar to the Caribbean today. This tropical paradise was the recipe for limestone.

When the plants and creatures died, their rotting remains collected on the sea floor and were buried in limey mud. Over millions of years layer upon layer of limey mud collected and squashed the layers below to make limestone. Today this limestone appears in different guises. The old coral reefs are very resistant and strong and now they stand proud and firm as rounded hills between Clitheroe and Malham. Impossible as it may seem Stebden Hill was once a coral reef island. Meanwhile the shallow water limey layers became pure light grey limestone like that at Gordale Scar. Features such as Ingleborough Cave started life as a tiny crack caused by the shrinking of the limey mud as the water was squeezed out of it. Over the years these cracks enlarged as water dribbled down and dissolved the sides. Today those cracks have become networks of disorientating caves.

If Yorkshire had kept its clear blue seas and idyllic islands it would appear in the Thomson sun brochure today. However Scotland had other plans and saved Yorkshire from becoming a package holiday destination. The trilobites had to pack their bags and the gritstone moved in.

Stanage, Froggatt, Gardom’s Edge and Brimham Rocks. All tough sounding names for strong and sturdy rocks. Fantastic walks along the gritstone edges, strenuous climbs with abrasive, rounded handholds and little pebbles for feet to teeter on, or the remains of a giant’s game of skittles over at Brimham Rocks. This typifies the harsh gritstone country that was responsible for snuffing out the limestone and dramatically altering the southern Pennine’s appearance all those millions of years ago.

While Yorkshire was basking in its tropical limestone seas, Scotland was working hard building mountains. By around 300 million years ago Scotland had built the equivalent of the Himalayan mountain range and these majestic mountains towered over Yorkshire.

Each time a tropical storm hit the mountains lots of rubble was washed down into Yorkshire’s limestone sea. The trilobites were squashed and the coral reefs smothered, turning Yorkshire into a murky lifeless sea. Nonetheless Yorkshire wasn’t going to give up its tropical paradise without a fight. Each time Scotland ran out of ammunition from the mountains the limestone seas flooded back in. This battle created layers of rocks that look a bit like a many-tiered cake. Yorkshire contributed the hard limestones, while Scotland provided layers of sandstone and soft dark shales.

Today the remains of this battleground appear in the northern Dales. You can see it at places like Hardraw Force near Hawes. Yorkshire’s tough limestone forms the top of the waterfall, Scotland’s sandstone makes the cliff face and the soft shale at the bottom makes a plunge pool. Another place is the stepped sides of Pen-y-Ghent with alternating limestones, sandstones and shales from this time.

Eventually Yorkshire lost its battle with the Scottish mountains and the limestone seas died away. Yorkshire became Scotland’s ‘Bangladesh’ and a huge delta with fingering streams and tugging tides was formed. Mud, sand and grit came tumbling down the rivers to the Yorkshire delta. The bigger pebbles would settle out first and then the smaller grains would float down slowly and sit on top. Some of the sand was laid down at an angle in underwater sand dunes. Each storm deposited a thick gritstone layer. Between storms softer muds settled.

Finally the Scottish mountains were diminished by the tropical storms and they began to run out of grit to throw at Yorkshire. Forests began to grow on the delta and the area became swampy.

The limestone and gritstone were buried and didn’t re-surface again for many millions of years. While they hibernated, Yorkshire sailed northwards on its part of the Earth’s jigsaw puzzle surface. About 30 million years ago Yorkshire turned the engines off and settled where it is today. The rocks below decided to push up and see the view. After a lot of erosion the gritstone and limestone got their first breath of fresh air and began to experience the Yorkshire weather. Wind and rain began to nibble at the fresh rocks. Pockmarks were created in the limestone, and caves enlarged. In the gritstone the weaker layers were picked at, rather like eating the filling of a sandwich but leaving the bread behind.

Today the gritstone looks quite old and wizened. Softer bits have been etched out, leaving big blocky layers. The thicker the layer, the bigger the storm that created it. Some of the most difficult gritstone climbs that involve struggling across a featureless block can be blamed on the biggest storms all those years ago. The long gritstone edges like Stanage and Froggatt exist because they are sitting on soft shales. As the shale wears away the gritstone becomes overhanging and eventually big blocks break off and roll down the hill. However a little bit of Yorkshire wind and rain can’t explain everything. Roll on the ice ages.

Around two million years ago the Earth’s climate suddenly flipped and big ice sheets started to grow at the poles. Why this happened is still debated, but changes in currents in the deep ocean probably had a part to play. To this day the ice sheets have waxed and waned as the Earth wobbles around the sun. If mankind hasn’t meddled with the climate too much we will be entering another ice age in a few thousand years - good news for winter mountaineers.
Each time the ice spreads its fingers during an ice age it carves new valleys, scrapes off topsoil and plucks up boulders the size of houses. When the ice departs it leaves behind a wreckage of stranded boulders, heaps of clay and new valleys and drainage patterns. Evidence of the ice is scattered around the dales and peaks.

Malham Cove once had a mighty waterfall plunging over its cliff. The cliff itself is the result of earth movements while Scotland was building its enormous mountain range. When the ice sheets from the last ice age began to melt, the meltwaters had to travel overland at first because the underground routes were all full of ice. The waters carved out a route down the Watlowes valley before nose-diving over Malham Cove. Nowadays the water takes the underground route and the Watlowes valley is dry. The limestone pavement at the top of Malham Cove was formed by ice sheets scouring the limestone and then rainwater dissolving the cracks.

The ice ages also left their mark at Brimham Rocks. When the last ice sheet departed, Yorkshire was a bit of a barren place, with no plants due to the lack of soil. Strong winds whistled in and bounced sand grains along the ground. The rocks at Brimham were sandblasted up to knee height, making the mushroom shaped blocks we see today.

Most recently the rocks have suffered miners and quarrymen hacking at their layers, while climbers and walkers swarm over their surfaces and pot holers explore their intestines. But what lies ahead for the gritstone and limestone? Another ice age? A greenhouse climate? Perhaps re-burial under the sea? Whatever it is the rocks will carry on watching the world go by for many years long after we have all gone.

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