The Fall of the Central Trilithon — a hypothesis machine

space = fall / pause · adjust sliders, then let it fall

The question

Was the Altar Stone still standing when Stone 55 came down — or already flat?

Preset runs

Hypothesis parameters

Initial lean of 55 Its centre of gravity clears the socket edge near ~9.3° — below that, it rocks back and holds.

Subsidence kick How suddenly the footing gives way.

Socket depth of 55 Gowland measured 56's at 2.4 m in 1901; 55's was notoriously shallow. Deeper = the base is held captive longer through the fall.

Sarsen strength Impact needed to snap 55 into 55a + 55b.

Tenon grip on lintel 156 How far the mortise‑and‑tenon joints drag 156 along with the fall before letting go.

Altar Stone footing How hard a blow the standing Altar Stone's bedding can absorb.

Playback speed

Result of this run

Trench notebook

— awaiting collapse —

What is fixed by evidence: Stone 55 fell and broke in antiquity — already down before the earliest reliable drawings. Stone 56 stood on (leaning) until it was straightened and concreted in 1901. Fragments 55a, 55b and lintel 156 rest today across the recumbent Altar Stone, which has never been fully excavated — it is pinned beneath them. Everything else here is a knob.