Lake sediments and glacial history in the High Arctic; evidence from east-central Ellesmere Island, Arctic
Bibliographic record
Abstract
Deciphering glacial history in many High Arctic localities is difficult because: 1) surficial deposits are often thin or non-existent, 2) vast tracts are underlain by soft and friable bedrock, 3) the churning effects of frost action and slope processes tend to eradicate traces of glaciation, 4) cold based ice caps leave little trace of their former presence, except where marginal drainage channels form on uphill slopes, and 5) significant areas still are covered by glacier ice. Where present, striae show that an area has been glaciated, hut until a technique is devised to determine when a given set of striae was inscribed, or when a striated surface became exposed to daylight (e.g. Phillips et al. 1986: Elmore & Phillips 1987), the timing of the glacial event responsible remains an enigma. One way of approaching the problem of dating glacial events, in the High Arctic as elsewhere, is to determine the age of organic deposits associated with till or outwash. Radiocarbon dating of the basal increment from a lake sediment core or a peat deposit provides a minimum age for deglaciation and for the onset of organic accumulation. In this connection the advent of "C dating by means of accelerator mass spectrometry (AMS) has provided an extremely powerful tool for determining the timing of events more precisely. For instance, the change from marine to lacustrine conditions or, in the case of a lake above the limit of Holocene marine submergence, the onset of lacus-trine moss growth can be pin-pointed much more accurately using this technique (Blake 1985). Available basal dates on reliable organic materials from lakes in east-central Ellesmere Island, an area underlain by granites. migmatites. and associated rocks of the Canadian Shield, do not exceed 9500 radiocarbon years. The oldest age determinations, among seven lakes dated, have been obtained along the outer
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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 | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".