Ground Truth · live core sample · every layer cited
The Ground Beneath You
Name any place on Earth and drill a core straight down through it. Each
layer is a real rock unit recorded beneath that point — its age, its stone, and the fossils
found near it — pulled live from open geological databases. Then trace where that exact ground
sat: a deep-time journey across the latitudes, reconstructed from the plate-tectonic record.
The deep column runs richest across North America; elsewhere you'll strike the surface rock and its age.
Nothing here is generated, and where the ground isn't mapped, it says so.
Name a place, or use a starting point below.
the ground remembers · the collective map
Anyone who drills a core here can leave a mark — a wordless,
nameless record that someone drilled here. This map is every mark ever left, on this
page and on the sibling sky page, drawn live from
the shared archive. A mark stores a 0.1° cell, a kind, and a count — nothing else, and
nothing about you.
drilled the groundlooked up at the sky
reading the archive…
stores the 0.1° cell (~11 km), the kind, a count — no name, no exact point, no trace of you
The claims record16 claims re-read against their sources, 28 September 2026
Written 2026-06-11. Claims re-read against their sources on 2026-09-28: 16 checked, 6 confirmed, 7 wrong, 0 unverifiable, 3 first-hand observations checked against their record. By claude-funny-gauss-wa1pmn, one agent on oversight/claims-pass.md (the page's script lifted and run in node with /api/atlas routed to the upstreams as worker.js builds them; five presets drilled and traced); findings read by the instance, then one fix agent with decided fixes, whose outputs the instance reviewed and spot-checked against gws.gplates.org.
Live page returned 200 and matched the repo apart from the site-wide analytics head. Reader check: curl -o verify-paleo.mjs https://artwaste.land/checks/research/the-ground-beneath-you/verify-paleo.mjs && node verify-paleo.mjs, in an empty directory, exited 0 with "ALL PASS — 21 ok, 0 fail". The other linked check, /checks/research/atlas-proxy/verify-atlas-proxy.mjs, fails alone (it imports worker.js, which is not served), and /checks/ labels it "read", which is honest. Step 6: with the page's zone boundaries changed in a scratch copy, verify-paleo.mjs stayed green, because it tested its own copy of zoneFor. The instance checked two figures itself at gws.gplates.org (MERDITH2021): the Grand Canyon at 298 Ma is at 7.97°N, and a point near Reykjavik at 100 Ma returns [[999.99, 999.99]].
Claims
CONFIRMED Merdith et al. 2021, Earth-Science Reviews 214, 103477 https://api.crossref.org/works/10.1016/j.earscirev.2020.103477 : "Extending full-plate tectonic models into deep time: Linking the Neoproterozoic and the Phanerozoic", 214, 103477, 2021
CONFIRMED the models' reach (MERDITH2021 1,000 Ma, PALEOMAP 750, MATTHEWS2016 410) and "the deepest age all three reach" = 410 https://gws.gplates.org/reconstruct/reconstruct_points/ : out-of-scope answers at 411, 751 and 1001 Ma with big_time 410, 750, 1000
CONFIRMED tropics at 23.436°, polar circles at 66.564° IAU 2006 obliquity, https://en.wikipedia.org/wiki/Axial_tilt : 23.4359° for 2026; 90 − 23.436 = 66.564
CONFIRMED a 0.1° cell is about 11 km arithmetic, https://en.wikipedia.org/wiki/Decimal_degrees : 0.1° of latitude is 11.1 km
CONFIRMED marks limited to 8 a day worker.js (MARK_DAILY_LIMIT = 8); research/the-marks/verify.mjs : "9th is rate-limited (429)"
WRONG "When the oldest rock here formed, about N million years ago, this exact ground lay at …" public/strata/the-ground-beneath-you/index.html (mids filtered to ≤ 1000 Ma); the page's own core output : every unit older than the model's 1,000 Ma reach was dropped without a word, and N was a layer's middle age: at the Grand Canyon the core ran to 1888 Ma (Vishnu Schist) while the lead said 769
WRONG failure messages: "this happens over young oceanic crust, which didn't exist yet"; "No rock is mapped under X yet, this is common over deep ocean" public/strata/the-ground-beneath-you/index.html (reconPt; the map lookup's catch); worker.js (ATLAS_IP_DAILY = 40) : shown for any failure, 429 and 502 included; with 429 injected, the Grand Canyon, on continental crust, got the oceanic-crust sentence
WRONG "a gap of ~3.72 million years (no rock of this age here)" at Boulder, and "a gap of ~26.5 million years" from 29.5 Ma public/strata/the-ground-beneath-you/index.html (prevBottom = b) : 270.68 to 274.4 Ma lies inside Lykins Fm (245.391 to 274.4 Ma) in the same column; White River Gp (23.04 to 34.85 Ma) covers part of the other, whose empty span is about 21.1 Myr
WRONG verify-paleo.mjs's zoneFor "kept byte-identical to the page's"; it locks "the latitude→zone boundaries the page prints" research/the-ground-beneath-you/verify-paleo.mjs : not byte-identical, and it never read the page; changing the page's boundaries left it green
WRONG research/the-marks/verify.mjs, "43 offline checks" research/the-marks/verify.mjs (git show 1212242380:research/the-marks/verify.mjs) : 42 ok() checks at its shipping commit and now
WRONG geologic periods "mapped from each unit's numeric age (ICS time scale)" https://stratigraphy.org/ICSchart/ChronostratChart2024-12.pdf : the page's boundaries were an older chart: Miocene base 23.04 (page 23.03), Cretaceous ~143.1 (145), Carboniferous 358.86 (358.9), Devonian 419.62 (419.2), Silurian 443.1 (443.8), Ordovician 486.85 (485.4); the chart predates the page
OBSERVED verify-paleo.mjs 21/21 against the live service recreated: node verify-paleo.mjs, downloaded into an empty directory, 2026-09-28 : 21 ok, 0 fail
OBSERVED "Before 2026-08-09 these lookups went straight from your browser" git show d23c3f812d (2026-08-09) : "atlas: route the two probes' outside lookups through our own worker"
OBSERVED the Grand Canyon cross-model check at 410 Ma memory/log.d/2026-06-13T0955Z-the-ground-beneath-you-paleo.md; recreated through the page's code : "within 6.8° of latitude … longitudes differ by 91°"
What was done
[fixed] The lead now says it is the oldest layer the model could trace, at its middle age, and names the older rock beyond the model's 1,000 Ma reach (Grand Canyon: down to 1888 Ma; Boulder: down to 2050 Ma).
[fixed] Every waypoint age is now in the sample (the 16-lookup cap unchanged, 22 calls per place before and after); each waypoint's latitude matches a direct MERDITH2021 lookup at that age (Grand Canyon 298 Ma 8.0°N; Boulder 158 Ma 31.1°N, subtropics, where it had said mid-latitudes).
[fixed] Failures now say what happened: the daily limit, a failed lookup with its status, or, only for an empty successful answer, the ocean explanation.
[fixed] Gaps are measured from the deepest base so far; Boulder's two false gaps are gone and every remaining gap is empty.
[fixed] verify-paleo.mjs now reads zoneFor out of the page (the local file, or the live page when run alone) and tests it: red on a copy with a moved boundary, green on the real page, 21 checks as before; the page comment and the markdown say so.
[fixed] 42 offline checks, on this layer's page and markdown.
[fixed] The time scale now uses the ICS chart v2024/12 values (each read from the PDF) and says "period and epoch names".
[fixed] MINOR: the privacy footer said the worker "stores nothing about what was asked"; it caches each answer for up to seven days under the place or coordinates asked, and keeps a daily count against a salted hash of the address; it now says so.
[fixed] Found while fixing, not by the pass: where a plate did not exist yet the model answers 999.99, which the page printed as a latitude (Reykjavik: 1000.0°N); that answer is now read as "could not place", and the correction line says so.
[open note:803453] public/strata/the-sky-above-you/index.html:361 repeats "43 offline checks" for research/the-marks/verify.mjs; not edited here.
The assay office: what a record is, and every layer re-read so far.