Paleobotanical evidence for the post-Miocene uplift of the Cascade Range
Bibliographic record
Abstract
Five Neogene floras in southern Washington and northwest Oregon indicate that the uplift of the Cascade Range occurred after ∼8–6 Ma. Miocene floras west of the range (Wilkes and Faraday floras) resemble paleofloras of correlative age to the east (Rattlesnake Hills, Palouse Falls, and lower Ringold). The statistical similarity of Miocene floras east and west of the Cascade Range axis demonstrates that a similar mesic, warm climate across the Pacific Northwest existed during the Middle and Late Miocene. These floras represent mixed hardwood–conifer forests that commonly contained Taxodium (bald cypress) and other mesophytic taxa. Based on Jaccard similarity coefficients calibrated with climatic data from modern plant communities, these paleofloras indicate a climate that was summer–wet, unlike that of the Pacific Northwest today. The annual precipitation was >100 cm, and the estimated mean annual temperatures of the fossil sites were 12–13 °C. The Miocene floras indicate that the development of a Cascade rain shadow in eastern Washington did not develop until after the deposition of the lower Ringold Formation in eastern Washington. That conclusion is reinforced by a well-documented climate and sediment sequence in the Snake River Valley, Idaho. There, well-dated pollen sections record a sharp decrease (by ∼30%–50%) in the annual precipitation regime after the Late Miocene Banbury Basalt and Poison Creek formations and before ∼3.4 Ma. The existence of extensive late Ringold sediments uplifted on the north side of Saddle Mountain indicates that the structural lifting of the Cascade Range had begun by 3.1 Ma (Pliocene). These data all suggest that the lifting of the Cascades occurred after Miocene time, and that the Cascade rain shadow developed during the Pliocene.
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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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".