Stratigraphy

The nomination metadata doesn't explicitly confirm these are bc rather than ad though the surrounding period ranges make bc the far more likely reading flagged here as an inference not a certainty since the underlying nomination text isn't available to check directly we can't check it we can't check it it's still going through the process of getting checked man wow So why? So pop-up matters because of what it's straight, straight, straight photography.

Stratigraphy implies about Tutuila's settlement history, not because of a visible structure.

It sits inside a real ongoing scholarly debate.

Frederick Pearl's 2004 study argued that interior mountain settlement on Tutuila began comparatively late, around 600 to 700 years ago, and tied Tutuila's ridgetop sites to Samoan oral tradition about a legendary war with Tonga.

that cut is literally a negative shape in the profile a bite taken out of earlier sediment anything sealed at the very bottom of that cut in the first fill that accumulates after the shaft was dug gives you a no later than date for the original construction if there's a sherd of pottery there or a bit of charcoal or an animal bone you can date that material and say the tunnel was already opened by this time higher up later fills might hold medieval roofing tiles early modern glass modern plastic Those tell you about later uses and backfilling episodes.

Stratigraphy is the story of all those events stacked on top of each other.

But stratigraphy alone doesn't give you calendar years.

For that, you need things that can be dated in absolute terms.

Radiometric dating lets us measure how long certain isotopes have been decaying inside minerals, turning radioactive clocks into age estimates for rocks.

Stratigraphy, the study of layered rocks, lets us line up sequences across regions, if this distinctive ash-bed appears here and there those places were recording the same moment in time index fossils the remains of species that were widespread but short-lived act like timestamps Find a particular trilobite in two separate outcrops and you know those layers are roughly the same age, even if they're on opposite sides of a continent.

But even when we can date things, there's another problem, time averaging.

A layer of mud a few centimetres thick might represent a year of quiet deposition.

Harder layers project outward, sheltering the surface below.

Stratigraphy gives the tower a quiet horizontal rhythm beneath its vertical form.

Those beds began as differences in ancient sediment.

One interval may have contained finer carbonate mud, another more shell debris, and another small amounts of clay or other material.