Nass River on the move: radar facies analysis of glaciofluvial sedimentation and its response to sea-level change in northwestern British Columbia
Bibliographic record
Abstract
The Nass Valley of northwestern British Columbia is a glacial fiord containing extensive glaciomarine and glaciofluvial sediments. Two parallel braidplains, separated by a bedrock ridge, were deposited within the fiord. Mapping of these deposits led to the hypothesis that the braidplains must have terminated at deltas. However, a lack of surface exposures meant that ground-penetrating radar was needed to investigate these deposits. Radar facies analysis aided in the identification of braidplain, braid delta and glaciomarine depositional environments, as well as underlying bedrock. Several deltas graded to different sea levels were discovered, allowing inferences to be made about the relationship of falling sea level to sediment architecture. The upper section of the western braidplain is graded to a sea level of 185 m above sea level (asl), indicating that the proto-Nass River flowed on the western side of the bedrock ridge when the sea was at that level. However, the river moved to the east side of the ridge as sea level fell, depositing the extensive Aiyansh Braidplain – Braid Delta, which is graded to a 152 m sea-level stand. Several other deltas also formed at this sea-level stand. Avulsion occurred and the river flowed on the west side of the ridge again when sea level fell to 134 m asl. The river remained in this position throughout late glacial time and eventually evolved into the modern Nass River. The coarse-grained deposits are indicative of forced regression, with both stepped-top attached and detached stratal architecture present.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".