Massive submarine sand dunes in the eastern Juan de Fuca Strait, British Columbia
Bibliographic record
Abstract
A field of very large submarine sand dunes in the eastern Strait of Juan de Fuca, British Columbia, has been surveyed with seismic reflection, sidescan sonar and multibeam bathymetric systems. The field is comprised of approximately 2.6x10 7 m 3 of sand and fine gravel (mean size > 0.5 mm). The largest of these dunes measures 25 m in height, 300 m in wavelength and 1200 m in width, comprising 9x10 6 m 3 of material. Its wavelength to water depth ratio (L/h) is 3.3 (typical for intertidal dunes) and height to water depth ratio (H/h) is 0.28 (larger than typical in any environment). Its vertical form index (L/H) is 12 indicating a steep dune, a dimension that is atypical for large dunes. Its modified symmetry index (MSI = [(stoss-side length/lee-side length)-1]) is 0.6, indicating only slight asymmetry. The lee slope is about 20° and stoss slope is 12°. The larger dunes in this field are classified as linear, slightly asymmetrical, stoss-erosional, lee-deposition, two-dimensional, very large dunes. They show net zero climb. A subsidiary set of sand waves exists on the larger dunes at an oblique angle. Whether the dunes are modern or relict is unconfirmed, but conditions do exist today that could construct these features. Currents in excess of 100 cm/s can be expected at depth in the Strait These currents have the potential of eroding and transporting material up to granule size. It is likely that deep flood tides and estuarine circulation during summer months construct the dunes. Most of the time the flow transports material only near the crest of the bedforms, giving them a concave-up appearance. The estuarine circulation may reverse during winter months, though less strong, resulting in reworking of the dunes and causing the near-symmetrical profile more typical of tidal bedforms. Clinoform bedding suggests net eastward migration. This combination of estuarine circulation, tidal forcing, bathymetric control accelerating currents, source material and size of the source material has resulted in the construction of some of the highest and steepest submarine bedforms documented in the literature. The question of dune age and stability remains unanswered but is of critical engineering importance with the presence of pipelines, sewage outfall and fibre optic cables in the area.
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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 | 0.000 | 0.000 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.094 | 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".