Stand on the crest of a dune and look inland. Then turn and look out to sea. Everything between those two views — beach, seaward slope, crest, dune plain, hollows, older dunes behind — is a dune profile. Read it well and you can tell whether that stretch of coast is gaining sand or losing it, which parts are healthiest, and whereabouts the sea got in last winter. It takes boots, an hour, and the habit of looking at the shape of the ground rather than just the view.
A profile is a cross-section, and a timeline
Pick a line running roughly perpendicular to the shore and walk it from the water's edge inland. A dune system is built from the sea backwards: sand blows off the beach, gets caught by the first plants tough enough to survive burial, and the dune grows upwards and inland. So walking inland is walking back in time. The low hummocks near the beach may be a few years old; heath a kilometre inland may have taken centuries.
That is why the order of the zones matters more than any single feature. If the sequence is jumbled — a wet slack right behind the beach, or dark, fixed grassland on the seaward face — something has happened. Storms, sand extraction, sea walls, or a blowout eating its way backwards through the dune line.
The five zones to look for
- Strandline and embryo dunes. The debris line of the last high tide, then small mounds of sand caught by sand couch, sea rocket and orache. These are the newest ground on the coast, and they shift constantly.
- Yellow dunes. The mobile foredune, dominated by marram grass, with plenty of bare sand between tussocks. Called yellow because the sand is still clean and shifting. This is the dune that takes the brunt of winter storms.
- Fixed dune grassland. Sometimes called grey dunes, after the lichen and moss crust on older surfaces. The sand is held, the soil has begun to darken, and you find red fescue, lady's bedstraw, thyme and a scatter of bare patches.
- Dune slack. Damp hollows where the water table reaches the surface. Look for rushes, marsh orchids, creeping willow. Slacks sit between dune ridges and are often the richest and rarest part of the system.
- Hind dunes, heath and scrub. The oldest, most sheltered ground inland, where heather, gorse, brambles and sometimes planted pine take hold.
Zone widths vary enormously. A squeezed dune system may have a foredune and almost nothing else; a wide one can run for kilometres inland.
Reading the seaward face: growing or retreating?
Look at the front of the foredune. A gently ramped face, with sand piling around the base of marram and fresh green shoots pushing through, points to accretion: the dune is building seawards. A near-vertical scarp, a metre or more high, with roots and rhizomes sticking out and undercut ledges at the base, is wave erosion — often cut in a single storm. Both can be true along one beach. Walk a few hundred metres and watch where the front changes character.
Blowouts are the other feature to notice. These are saucer- or trough-shaped hollows with steep sandy sides, where wind has stripped sand away from a gap in the vegetation. Small ones are normal and even useful; they keep bare sand in the system. A large blowout cutting clean through the front line is a warning sign, especially if its floor is below the level of the surrounding slacks.
Reading the interior
Inland, the questions change. Fixed dune grassland should be a mosaic: short turf, moss, lichen crust, and patches of open sand. Bare sand is not a fault. Many dune plants and insects — a good number of them rare — need it to germinate or nest. A uniform carpet of coarse grass with no bare ground at all often means the site is under-grazed or no longer disturbed, and you may see scrub and saplings creeping in behind it.
In the slacks, note whether the hollows hold water. Damp ground with rushes and orchids in early summer is doing its job. A hollow that is bone dry, with rank grass and crack-lipped mud, may simply be seasonal drawdown, or it may point to drainage ditches and a falling water table. Look for straight channels or old grips cutting across the dune plain — a common legacy of post-war agricultural improvement.
Six things to record on any walk
- The direction of your line and roughly how far you walked.
- The shape and height of the foredune front — ramp or scarp?
- Where continuous vegetation begins. That is the dune toe.
- The width of the yellow dune zone. Narrow usually means squeezed.
- How much bare sand there is in the interior, and where it lies.
- Obvious human pressure: worn paths, fire scars, dumped material, ditches, sea defences.
Sketch it, don't over-measure
A quick pencil cross-section beats a folder of numbers you never look at again. Draw a horizontal line for distance and a vertical one for height, exaggerate the vertical so the shape reads clearly, and mark where each zone starts and ends. Write in the plants you can name and a question mark against the ones you cannot. Note the date, the weather over the previous week, and whether the wind has been onshore.
Return to the same spot in three months and sketch it again. The difference between the two drawings tells you more than either one alone.
Your first hour on the sand
Start at a signed access point and follow an existing path to the beach rather than crossing the dunes at random — dune vegetation is easily damaged and slow to recover. Choose a line, walk seawards to the water's edge, then turn and walk steadily inland, stopping every so often to look back. Note the zones in order. Note the shape of the front. Note the bare sand.
Keep an eye on the tide and on soft ground; dune faces can slump, and a scarp that looks solid from below may be undercut. Many dune systems are protected sites or nature reserves, so check local signage and keep clear of roped-off areas, which usually mark nesting birds on the upper beach.
Do this twice and you will start reading dunes the way you read a street: not as scenery, but as a place with a history and a direction of travel.
Photo: Michaela St / Pexels
