The tephra stratigraphy of two lakes in south-central British Columbia, Canada and its implications for mid-late Holocene volcanic activity at Glacier Peak and Mount St. Helens, Washington, USA
Bibliographic record
Abstract
Several mid-late Holocene Glacier Peak tephras along with Mazama and Mount St. Helens Wn and P tephras were found in cores from Cooley and Rockslide lakes in southeastern British Columbia, ∼300 km northeast of Glacier Peak. The sediments in Cooley Lake host the late Holocene Glacier Peak A tephra (2010 calibrated (cal) years BP), four separate Glacier Peak Dusty Creek (GPDC) tephras (57805830 cal years BP), and a Glacier Peak set D tephra (6060 cal years BP). This is the first report of Glacier Peak A and D tephras in British Columbia. The A tephra has been correlated on the basis of glass composition and age to a late Holocene Glacier Peak tephra in the sediments of Big Twin Lake, 75 km northeast of Glacier Peak. The glasses in the four GPDC tephra layers from Cooley Lake are compositionally indistinguishable from those in Mount Barr Cirque and Frozen lakes in southwestern British Columbia. The layers likely represent four eruptions taking place over 50 years. Although set D tephra has not been correlated to a known proximal or distal deposit, its glass bears the Glacier Peak glass compositional signature and its interpolated age corresponds to the initiation of the set D eruptive period. The presence of GPDC tephra in lake sediments across southern British Columbia suggests a broad plume trajectory to the north and northeast, whereas the apparent absence of the A and D tephras in all but Cooley Lake suggest plumes with a northeasterly direction.
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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 | 0.003 | 0.004 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".