Quantifying Lake Athabasca (Canada) water level during the ‘Little Ice Age’ highstand from palaeolimnological and geophysical analyses of a transgressive barrier-beach complex
Bibliographic record
Abstract
We combine multiproxy palaeolimnological and geophysical analyses of a barrier-beach complex to estimate the water level of a sustained Lake Athabasca (Canada) highstand during the ‘Little Ice Age’ (LIA; 1600—1900 CE). Palaeolimnological analyses on sediment cores from the lagoon behind the barrier indicate high water levels during the LIA, controlled by subsurface hydrological connection with Lake Athabasca. Key features in the LIA stratigraphic interval are sand laminations deposited by overwash events and low C/N ratios reflecting deposition of predominantly aquatic organic matter. Ground penetrating radar profiles of the barrier reveal a depositional transgression sequence composed of waterlain landward-dipping foreset beds and horizontal topset beds, overlain by aeolian deposits. Stratigraphic relations suggest that the LIA washover deposits in the lagoon formed as the barrier was actively translating landward, and were generated by high-water events on Lake Athabasca that overtopped the barrier. This indicates Lake Athabasca rose to at least the elevation defined by the contact between the waterlain and aeolian sediments in the barrier, which is >4 m above the historical daily average from gauged records available since 1930 and likely represents storm events during the highstand. Assuming a similar relation between daily average and maximum lake level as in the historical gauge record, our findings suggest that Lake Athabasca was on average 2.3 m higher during the LIA than present day. Extrapolation of this high-water plane into the adjacent Peace-Athabasca Delta indicates that 70% of the modern landscape was frequently and perennially flooded until very recently, consistent with palaeolimnological evidence from several lakes in the delta.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.001 | 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".