The Erosion Line

Annual Retreat, Metres Lost

Measured each March from a fixed baseline post set back from the 2011 cliff edge, tape run perpendicular to the line to the nearest visible break. A year with a bad winter storm reads high; a quiet year can read close to zero, which isn't error, it's the cliff waiting.

2019

1.2^m

2020

0.6^m

2021

2.4^m

2022

0.9^m

2023

4.1^m

2024

1.0^m

2025

1.7^m

Running total since the baseline was set: 11.9m. The 2023 spike followed the wet January that year — six named storms in five weeks saturated the till cap and brought down a section that had looked stable for a decade.

Photo-Point Comparison

Four markers, driven rebar with a numbered cap, positioned 40m apart along the top path. Same camera height, same focal length, same low-tide window each visit.

Marker 1Slumped face, now vegetated at the toe — oldest stable section, retreat under 0.3m/yr

Marker 2Clean vertical face, active — this section carried the 2023 loss

Marker 3Overhang visible since 2022, expected to fail within two seasons

Marker 4Boulder clay slope, slow creep rather than collapse, retreat steady at 0.5m/yr

Why It Fails Like This

Topsoil / till cap~1.2m, permeable, saturates fast in winter, adds load to the layer below

Boulder clay~6m, low permeability, holds water at the boundary, the usual failure plane

Laminated silts~4m, weak in shear when wet, slumps rather than shears cleanly

Chalkbase, stable, undercut by wave action at the toe during storm surge

The pattern is always the same: water perches on the clay-silt boundary through winter, the silt loses shear strength, and a block lets go along a roughly planar surface rather than crumbling — which is why the retreat comes in metre-scale steps in a bad year rather than a steady inch-by-inch creep.

Next Survey

14 March 2027

Weather permitting — the tape measurement needs a low spring tide and no active slip in progress at the face.