How to read a landscape
Next time you're on a train with an hour to kill, don't look at your phone. Look out of the window, and look past the fields to the shape they're draped over.
Landscape isn't scenery. It's the visible outcome of a long argument between rock that resists and water and ice that never stop, and most of that argument is still legible from a lay-by if you know what you're looking at.
You need about six habits. Here they are.
Read the cross-section before anything else
Stand at the end of a valley and squint at its profile — the shape you'd see if you sliced it across. That shape is the most informative thing in view, because rivers and glaciers cut in completely different ways and leave completely different signatures.
A river cuts down. It's a narrow tool working along a single line on the valley floor, and everything above that line is left to the weather, which loosens it and lets gravity drag it towards the stream. You get a V: steep sides running down to a floor barely wider than the water. Mountain streams in country the ice never reached do this everywhere.
A glacier isn't a narrow tool. It fills the valley, leans on the floor and both walls at the same time, and grinds all three. It also can't be bothered to go round things. You get a U — a broad flat floor, steep sides — and a valley that runs unnervingly straight, with the ends of the ridges that used to poke into it sliced off. Those are truncated spurs, and once you've spotted one you'll keep seeing them in Snowdonia, the Lake District and the Highlands.
Glengesh Pass in County Donegal, at the top of this piece, is the textbook version. There's a river in the bottom of it, and the river is far too small to have built what it's sitting in. That mismatch has its own name. A misfit stream is a river occupying a valley that something bigger made.
Ice leaves boulders in the wrong places
The most obvious thing glaciers do is move rock a long way and then drop it without explanation.
An erratic is a boulder that doesn't match the ground it's sitting on. If you're standing on pale limestone and there's a lump of dark, gritty sandstone the size of a car parked on top of it, no river put it there. At Norber in the Yorkshire Dales, blocks of Silurian greywacke sit on Carboniferous limestone — older rock resting on younger, several hundred metres from where it came from. That's ice. Geologists spent much of the nineteenth century tracing erratics back to their sources, which is how the extent of the ice sheets was first mapped, before anyone could drill a core to check.
Then there are drumlins, and they're worth learning because they're common and almost nobody notices them. A drumlin is a smooth, elongated hill, steeper at one end and tapering at the other, like an upturned spoon. They come in swarms — County Down and the country round Clew Bay in Ireland are full of them, and so is a lot of Cumbria. Ice moulded them, and the blunt end faces the direction the ice came from. So a field of drumlins is a compass. It tells you which way the ice was going, thousands of years after the ice went.
Moraines are cruder: heaps of unsorted rubbish bulldozed into ridges. A lateral moraine runs along where the edge of the glacier was. A terminal moraine sits across the valley where it stopped, and if it's big enough it dams the valley and you get a lake behind it. A great many lakes exist for exactly this dull reason.
Up at the top, look for corries — armchair hollows scooped out of the mountainside, usually with a steep back wall and often with a small round lake sitting in the floor. In Wales they're cwms, in Scotland coires, and in the Alps they're cirques. They're where the glaciers were born. Two corries eating into the same ridge from opposite sides leave a knife-edge between them, which is an arête; Striding Edge on Helvellyn is the famous English one. Three or more chewing at the same summit leave a horn, of which the Matterhorn is the advertisement.
Two smaller tells. Hanging valleys: a side valley whose floor stops abruptly high up the wall of the main valley, usually with a waterfall coming out of it. The small tributary glacier couldn't cut as deep as the big trunk glacier, so when the ice left, the side valley was stranded. And roches moutonnées — bedrock humps that are smooth and scratched on one side and rough and torn on the other. The smooth side faced the oncoming ice, which polished it. The ragged side is where the ice froze onto the rock and ripped chunks away as it moved on.
Rivers keep their old floors
Watch a river long enough and it wanders. Water on the outside of a bend moves faster and cuts; water on the inside slows and dumps sand. So bends get bigger, and eventually the neck of a loop is thin enough that a flood cuts straight across it and abandons the loop as a crescent of standing water. That's an oxbow lake, and even after it silts up you can often read the old curve as a damp line in a field.
Terraces are the better trick, though, and the one that gets missed.
A river builds a flat floodplain for itself. If the land then rises, or sea level falls, or the river's load of sediment changes, it starts cutting down through its own floodplain — and the old floor is left as a flat bench along the valley side, well above the current water. Do it repeatedly and you get a flight of steps. The Thames has several of these, and the reason it matters isn't scenery: the gravel of the older terraces is where a lot of Britain's early stone tools and extinct animal bones turn up, because those were the ground surfaces people and mammoths were standing on. Villages tend to sit on terraces too. They're flat, they're near water, and they don't flood.
Waterfalls are usually a hardness problem. Where a river crosses from a resistant band of rock onto a weaker one, the weak rock wears away faster, the hard band is left standing proud, and the fall retreats slowly upstream, leaving a gorge behind it. High Force in Teesdale drops over the Whin Sill, a sheet of hard dolerite injected into softer limestone and shale about 295 million years ago. Niagara does the same thing on a bigger budget. The gorge below the falls is the record of where the falls used to be.
Hard rock stands up, soft rock doesn't
Most of lowland England is built from layers of sedimentary rock, gently tilted, with the harder layers — chalk, limestone, some sandstones — standing above the softer clays either side. Erosion has done the rest.
Which gives you the single most useful shape in British landscape: the escarpment, with a steep face on one side and a long gentle back on the other. It looks like someone tilted a shelf. The steep face is the scarp, and it cuts across the layers. The long back is the dip slope, and it runs along the top of a layer, following the tilt of the rock itself. Get the two the right way round and you instantly know which way the beds are dipping, and therefore what you'd find if you walked down the gentle side. The Cotswold edge above Cheltenham does this. So do the North and South Downs, and the Chilterns.
Now look at the bottom of the scarp for a line of villages.
They're there because water is. Chalk and limestone are permeable — rain sinks straight through them rather than running off — so the top of the escarpment is dry, and the water travels down through the rock until it hits an impermeable clay underneath and is forced sideways and out. That line of springs is where people settled, and spring-line villages are strung along the foot of chalk escarpments across southern England in a way that looks like planning and is actually plumbing.
Bedding is a record of what the rock has been through
Sedimentary rock is laid down flat and in order, oldest at the bottom. Nicolas Steno worked that out in 1669, and it's still the first thing anyone uses at an outcrop. So any time you see layers that aren't flat, something has moved them.
Folds come in two flavours and both are visible in road cuttings. An anticline arches up; a syncline sags down. The counter-intuitive part is that anticlines often end up as valleys, because arching a layer stretches and cracks its crest, and cracked rock erodes first. The Weald, between the North and South Downs, is the classic case — a huge eroded anticline where the chalk that once ran over the top has been stripped away and the older rocks underneath are exposed in the middle. The Downs on either side are the surviving edges of that chalk, tilting away in opposite directions. Once you know that, the whole of south-east England makes a sort of sense.
Faults are breaks with movement across them. Normal faults happen where the crust is being pulled apart, and one side slides down. Reverse and thrust faults happen where it's being squeezed, and one slab is shoved up and over another. Strike-slip faults move sideways: the Great Glen Fault runs dead straight across Scotland from Fort William to Inverness and has slid horizontally by tens of kilometres. Loch Ness sits in it because shattered rock along a fault is easy to erode, and the ice took the easy route.
And then unconformities, which are the good ones. An unconformity is a surface where the rock record has a gap: one set of beds sitting on another set at a different angle, with the missing time invisible in between. In 1788 James Hutton took John Playfair and James Hall by boat to Siccar Point on the Berwickshire coast and showed them near-vertical greywacke with almost horizontal red sandstone lying across the top of it. Vertical beds had to have been laid down flat, buried, folded, uplifted and planed off by erosion before the sandstone could be dropped on them. Playfair wrote afterwards that the mind grew giddy looking so far into the abyss of time. He was looking at a gap of roughly 65 million years, in one cliff, on a wet afternoon.
Absences count as evidence
Chalk downland is full of valleys with no rivers in them, which is odd given that chalk soaks up water rather than shedding it. The usual explanation is cold. During the last glacial period, southern England wasn't under ice but was permanently frozen ground, and frozen chalk isn't permeable at all. Meltwater in the brief summers had nowhere to go but across the surface, so it cut valleys. Then the ground thawed, the chalk went back to swallowing rain, and the rivers vanished and left their valleys behind.
Limestone does the same disappearing trick without needing an ice age. Rain is mildly acidic and limestone dissolves in it, so the water goes underground through joints and enlarges them into caves, and the surface above is left dry, with sinkholes and gorges and stream beds that only run after heavy weather. Where a glacier scraped the soil off a limestone bench and left bare rock, the joints widen into a grid of slots — clints for the blocks, grikes for the gaps — which is what you're walking across at Malham.
Trees are worth reading too, though the answer is usually people rather than geology. Bare moorland at 400 metres in Britain is not naturally treeless. It's treeless because of centuries of grazing, burning and drainage, and the peat underneath it often contains the stumps and pollen of the woodland that used to be there. Where the tree line looks suspiciously flat and low, sheep drew it.
The coast keeps moving the goalposts
Sea level isn't a fixed datum, and neither is the land.
Round much of Scotland you can walk along a flat strip of ground backed by an old cliff, well above the modern beach, sometimes with rounded pebbles still lying about on it. Those are raised beaches. The ice that sat on Scotland was kilometres thick and pressed the crust down under its weight; when it melted, the land began springing back, and it's still rising today. The north of Britain is going up by a millimetre or two a year while the south-east quietly sinks — one end of a very slow see-saw.
The opposite shows up in south-west England, where the coast is full of long branching inlets that look exactly like drowned river valleys, because they are. As the ice sheets melted, sea level rose by roughly 120 metres worldwide and flooded the lower reaches of rivers. The Fal and the Dart are valleys with the sea in them. Their branching, tree-like plan is a river's, not the sea's; waves don't make shapes like that.
People are a geological agent now
Half of what you're looking at in a settled landscape was arranged by somebody, and it's often older than it looks.
Corrugations in a pasture, running in long parallel waves about five to ten metres apart, are ridge and furrow — medieval ploughing, preserved because the field was turned to grass afterwards and never ploughed flat. Terraces stepping across a steep slope may be lynchets, where centuries of ploughing dragged soil downhill until it piled against the field boundary. Straight hedges enclosing rectangular fields usually mean parliamentary enclosure, mostly late eighteenth and early nineteenth century; wiggly hedges with lots of different shrub species in them are generally much older. Quarries, spoil heaps, mill leats, drained fen, canalised rivers, a reservoir where a valley used to be.
Even the position of the town is geology, most of the time. Bridging point, spring line, gap through an escarpment, the lowest place a river could be crossed on foot, a defensible lump of hard rock in soft country. Durham, Edinburgh, Lincoln, Oxford — all of them sited by the rock before anyone drew a plan.
Nothing out there is finished
The last thing to get used to is that none of this is a still photograph. It's a very slow film, and you're seeing one frame.
Rivers are cutting tonight. Cliffs are retreating at rates you could measure with a tape measure over a decade. The scarp faces of the Downs are moving slowly backwards. Scotland is rising, the south-east is sinking, and in the geologically near future the ice may well come back and do the whole thing again, because there've been repeated glacials through the last couple of million years and there's no obvious reason for the pattern to have stopped.
Which is the useful reframing. A landscape isn't a place. It's a process caught mid-sentence, and the shapes are the handwriting.
Start with the cross-section. Everything else follows from that.
