Correlation of Tephra Marker Beds in Latest Pleistocene and Holocene Fill of the Submerged Lower Columbia River Valley, Washington and Oregon, U.S.A
Bibliographic record
Abstract
Peterson, C.; Minor, R.; Gates, E.B.; Vanderburgh, S., and Carlisle, K., 2012. Correlation of tephra marker beds in latest Pleistocene and Holocene fill of the submerged Lower Columbia River Valley, Washington and Oregon, U.S.A.Seven tephra layers in the submerged fill of the Lower Columbia River Valley (LCRV) are radiocarbon dated (0.5–13 ka in age). They are correlated to reported eruption sources in the adjacent Cascade Range volcanic arc. The tephras provide a stratigraphic framework for the transgressive depositional filling of the tidal Columbia River system (∼200 km in length). The thickest and most continuous tephra marker beds in the LCRV are from the Mount Mazama set-O eruption at 7.7 ka. The eruption source for this tephra (1–10 m thick) is confirmed by glass geochemistry and radiocarbon dating of borehole samples from depths of −13 to −38 m (North American Vertical Datum of 1988 [NAVD88]). The Mazama set-O tephra conveniently divides the depositional sequences of the Early Holocene from the Late Holocene in the deep valley fill (50–120 m axial valley depth). A much deeper tephra, at −84 m, is attributed to Mount St. Helens set-S/J eruptions at ∼13 ka, which confirms the end of the Glacial Lake Missoula Flooding in the LCRV. Late Holocene tephra marker beds in the LCRV include the Mount St. Helens set-J/P eruptions (2.5–4.0 ka), set-W/T eruptions (∼AD 1480), and an intermediate-depth tephra, attributed to a Mount St. Helens or Mount Adams eruption (∼1.3 ka). The Late Holocene tephras date the ages of tidal flats and extensive floodplains throughout the length of the LCRV. The Late Holocene marker beds provide the first widespread constraints on wetland sedimentation rates and preservation potentials for archaeology sites in the LCRV.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 teacher head, 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".