Proglacial-lake nomenclature graph

A small framework for naming glacial proglacial lakes consistently, and for representing the whole naming scheme as a directed temporal graph.

Proglacial lakes split and merge as ice advances and retreats, and their outlets jump between drainage basins. The literature names the results inconsistently — sometimes a merged lake gets a new combined name (Lake Superior from glacial Lakes Duluth + Minong), sometimes a co-equal lake is quietly demoted to a "phase" of its neighbour (Lake Agassiz absorbing Lake Ojibway as its "Ojibway phase," even though the merged body is elsewhere called Lake Agassiz-Ojibway). This repo makes the scheme explicit so the inconsistencies are visible and fixable.

The rule

Three moves, one criterion — what the ice is doing:

situation	naming
two water bodies separated by ice at the same time	distinct names (two lakes)
the ice between them clears and they join	one lake, a NEW combined name
one lake drops through successive outlets over time	one lake, phase names

Corollaries:

• A migrating outlet — even to a different ocean — is still one lake. Lake Agassiz flipped Gulf → Great Lakes → Arctic and stayed Agassiz; the Mohawk-lowland lake flipped Susquehanna → Hudson and stayed one lake.
• A merge of two independently-named lakes takes a new combined name, applied consistently. Not "Lake A (with a B phase)." This is the rule Superior obeys and that "Lake Agassiz" (post-Ojibway) violates — see docs/case-studies/agassiz-ojibway.md.

The graph

• Node = a named water body: a whole lake, or one outlet-controlled phase of a lake.
• Edge = a transition:
  • phase — same lake, next lower outlet, same drainage direction
  • outlet_shift — same lake, outlet jumps to a different basin/ocean
  • merge — two+ ice-separated lakes join into one lake with a new name
  • split — one lake divided by advancing ice (→ two names)
  • drain — terminal drawdown / catastrophic release

The consistency invariant: a merge edge must target a node whose name is new/combined, not a verbatim continuation of a parent. build_graph.py checks this and warns on violations.

Quickstart

python src/build_graph.py     # data/lakes.yaml -> build/lakes.{dot,svg,png}

Data lives in data/lakes.yaml; rules in docs/naming-rules.md; worked examples in docs/case-studies/.

Status

Early / exploratory. The schema (node & edge fields, edge types) is expected to change — treat data/lakes.yaml as a draft. Current examples: Lake Agassiz → Agassiz-Ojibway; Lake Superior (Duluth + Minong); the Mohawk-lowland lake (from the NY Mohawk luminescence project), including its unresolved terminal merger (Iroquois to the west vs. Glacial Lake Albany to the east — see the case study).

License

This repository is dual-licensed, by content type:

• Code — everything under src/ and tests/ — is licensed under the GNU General Public License v3.0 or later (GPL-3.0-or-later); see LICENSE.
• Data and documentation — data/, docs/, this README, and the generated graph under build/ — are licensed under the Creative Commons Attribution-ShareAlike 4.0 International license (CC-BY-SA-4.0); see LICENSE-CC-BY-SA-4.0.txt.

The PDFs under literature/ are third-party copyrighted works. They are git-ignored, not part of this repository, and not covered by either license — literature/references.md records the citations.