Formation of the Lake District Landscape: Geology, Climate and Humans

During this year’s Ullswater Outdoor Fest, the Friends of the Ullswater Way organised a series of five talks on the history and heritage of the valley. The third was by Geoff Cowell  on the Formation of the Lake District Landscape. Geoff is a Voluntary Ranger for the National Park. He leads Guided Walks, many in the Ullswater Valley, and is involved with the Archaeology Network.

Geoff CowellHave you ever thought how the Lake District Landscape came to be as we know it today? How were the mountains, lakes and valleys formed? When did humans first settle in Cumbria and how has Homo sapiens changed the landscape? Geoff Cowell’s fascinating talk took us on a journey through time, from volcanic eruptions 500 million years ago to ice sheets and glaciers 20,000 years ago and finally to our Neolithic ancestors who began to change the Lake District landscape 6000 years ago, clearing the forests for agriculture, using the green rock of the Langdales to craft axeheads, and constructing stone circles and other structures that we can still see today. After Geoff’s inspiring talk I for one will be looking at our landscape through much more curious eyes – looking beyond its beauty for clues about its past.

A land carved from rock

Our journey began 500 million years ago with the first big surprise. A map of the time shows England and Wales close to the South Pole on the landmass of Avalonia and nowhere near Scotland and Northern Ireland. These were part of Laurentia and lay close to the equator. However, in the next 100 million years all this was to change as movements in the earth’s tectonic plates brought the landmasses together to form the supercontinent Pangea. The Iapetus Ocean became narrower and narrower as the plates came together, volcanoes erupted as one plate pushed under the other and rocks near the plate boundaries were folded and uplifted to form mountains.

The geological history of the Lake District is written in the rocks below our feet. Rocks formed 500 million years ago came from muddy seafloor sediments compacted and then uplifted as the landmasses collided. They form the Skiddaw Slates. Volcanic rocks were formed from the ash and lava produced as volcanoes erupted. These are very hard and resistant to erosion and have given rise to some of our highest craggiest mountains, for example Helvellyn. The Lake District also has limestone rocks originating from the sediments of the tropical Iapetus Ocean and sandstone formed about 250 million years ago when Cumbria was situated where the Sahara is today. Later earth movements have shifted, folded and uplifted all these different rocks to form the mountainous landscape we know today. Ice sheets and melt waters have then eroded and sculpted it further.

A land sculpted by water

For the last 2.6 million years the Earth’s climate has fluctuated between hot and cold periods. In cold periods ice sheets and glaciers have covered the Lake District, spreading out in a radial drainage pattern that has given rise to the pattern of lakes we see today. They seem to form the spokes of a wheel with the hub more or less at Dunmail Raise.

The most recent glaciation lasted from 26,000 to 10,000 years ago. As the glaciers slowly retreated they carved the valleys and created the lakes, tarns and other landscape features we see today.

Geoff went on to explain how some familiar landscape features are created. Corries, horseshoe in shape, are found near mountain summits where glaciers begin. Snow collects in a hollow, and as more and more falls it is compressed into glacier ice. As the glacier begins to move it erodes the hollow making it bigger and deeper. Rocks plucked from the back wall of the corrie are deposited on its edge to form a lip so when the ice melts a circular lake is often formed. Red Tarn on Helvellyn is an example.

Red Tarn
Red Tarn: Photo Credit Paul Harris

Knife edge ridges such as Helvellyn’s Striding Edge are also glacial features. They are called arêtes and are formed when 2 neighbouring corries run back to back. As the glaciers on either side each erode their side of the ridge, the edge becomes steeper and the ridge narrower.

Striding Edge
Striding Edge: Photo Credit Paul Harris

The valley floors are also sculpted by the retreating glaciers. Glaciers cut U-shaped valleys with a flat floor and steep sides. Soft rocks are eroded more readily than hard ones, cutting deeper troughs that become ribbon lakes once the glacier has retreated. Ullswater is just one of the Lake District’s ribbon lakes.

If a glacier hits an outcrop of very hard rock it will flow over and around it, leaving a rock mount smoothed by abrasion from the glacier and often with a jagged face on the lee side due to ‘plucking’. These are called roches moutonnée.

As glaciers move, they gather debris from the floor and sides of the valley and as they melt they drop this debris to form moraines. Lateral moraines are at the side of the valley and terminal moraines, sometimes called drumlins are at the end.

Just like rivers, glaciers often have tributaries – smaller glaciers that join the main one. As the main glacier erodes deeper into the valley, the tributary is left higher up the steep sides of the glacier and, as the ice melts its U-shaped valley is left ‘hanging’ above the main one, often with a waterfall tumbling over its edge. Glencoyne is an example of such a hanging valley, caused by a glacier along Ullswater cutting across the one coming down Glencoyne.

A landscape modified by humans

In the third part of his talk, Geoff introduced Homo sapiens. The first evidence of humans in Cumbria is from Kirkhead Hill above Morecombe Bay where Palaeolithic flints, estimated to be 11,000 yrs old, have been found.

In the Mesolithic, the climate became warmer and wetter and, as a result, by 6,000 years ago the Cumbrian landscape was covered in deciduous forest, home to deer, elk, auric and smaller mammals. Because of the dense forest inland, our Mesolithic hunter-gatherer ancestors probably kept mainly to the coast, near estuaries where rivers provided a constant supply of fresh water. Flint-chipping sites have been found at Eskmeals and at Walney and evidence of wooden raft-like structures suggest semi-permanent or permanent settlements. There is also evidence of charcoal burning and small-scale forest clearance. This is the first evidence of humans changing the appearance of the landscape.

It is from the Neolithic, 6,500 – 4,350 years ago, that we have more visible evidence of human activity in the form of stone circles, cairns and axes. The axe factory on Pike O Stickle in the Langdales is the most significant Neolithic find in Cumbria. Axeheads fashioned from its green volcanic rock can be found all over Britain and it seems they were used not only as weapons but also for ritualistic purposes.

Cockpit Stone Circle
Cockpit Stone Circle: Photo Credit Janet Wedgwood

At this time henges and stone circles, such as Cockpit on Moor Divock, were created across Cumbria. We find the first evidence of agriculture – seeds of emmer and einkhorn wheats and also of barley. We also find querns, stones on which the grain was ground into flour, and marks made by the ard, a type of plough. As agriculture increased people settled more permanently but, without fertilisers, the yields fell over time and they were forced to move on, clearing more areas of forest. Their sharp polished stone axes felled trees faster than flint and the surrounding undergrowth was burnt. Their grazing animals prevented the forest from regenerating on the old fields so the forests began to disappear.

The Bronze Age was centred on Crete and the trade expanded across continental Europe to reach Britain about 4,000 years ago. At this time warmer climates meant that people could settle on higher ground. Agriculture meant there was more food available and, once manure was used as fertiliser and fields were left fallow to recover, longer-term settlements were possible. At this time we see the first evidence of permanent boundaries marking land holdings.

MoorDivockRingCairn
Moor Divock Ring Cairn: Photo Credit Geoff Cowell

By the Iron Age, 2,800 years ago, human impact on the landscape was increasing still further. The landscape was more open and probably more organised, with woodlands managed and a lot of forest cleared to create fields and provide wood for construction. The harvest was stored to use throughout the year. There was mining for iron ore but probably on a very small scale. There are signs at Hartsop of a settlement that is Iron Age to Roman.

Hartsop Settlement
Beyond the wall are the earthworks of the Hartsop Settlement. Photo Credit Anne Clarke

So, by the time we reach the Iron Age, humans have already had a significant impact on the landscape through forest clearance and by creating enclosures, settlements and monuments.

Inspired by Geoff, when I next walk the Ullswater Way I will try to imagine the valley at different times in its history – when glaciers were carving out the valleys, or when, as the climate warmed and rainfall increased, the area was covered in dense forest.  I will try to imagine how life might have been during Neolithic or Iron Age times.

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