Gravel-sand transition in the mixed bedrock-alluvial Congaree River, SC. Preliminary results on gravel mobility 
Bibliographic record
Abstract
Gravel-sand transitions are generally characterized by a decline in bed slope and surface grain size from about 10 mm to 1 mm over a range of distances. Values vary from a few hundred meters on relatively small streams in Scotland and Canada, to tens of kilometers on the Fly River in Papua New Guinea and on the Fraser River in Canada. Gravel-sand transitions form for different reasons such as preferential breakdown of sediment clasts, downstream propagation of a gravel front, changes in sand transport mode and different mobility between sand and gravel. Recent field work on the Congaree River, South Carolina, revealed the intermittent presence of gravel bars and sand bars, as well as bedrock channel reaches along the upper 35 km. At ~30 km downstream of the reach where gravel is observed, the river channel and the bars are made of fairly uniform sand with median grain size of 0.6 mm. It is thus reasonable to expect the presence of a gradual gravel-sand transition. Field measurements of bed elevation show that this gravel sand transition is not associated with significant bed slope change. We hypothesize that the presence of the gradual transition is due to the increased gravel transport capacity in the presence of sand. Further, the resistant bedrock in the mixed bedrock-alluvium reach may prevent the abrupt change in bed slope observed in other gravel-sand transitions.
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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 | 0.000 |
| 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".