Light penetration into Clarens sandstone and implications for deterioration of San rock art
Bibliographic record
Abstract
Abstract In respect to the weathering of cave art exposed to the sun, cognizance has yet to be taken of the modified thermal conditions and the potential for endolithic biotic activity where the art is located on a light‐transmissive lithology. Where light penetrates rock, the light‐to‐heat transfer is not solely at the surface, and this leads to a thermal gradient that is different from where the paintings are located (and all transfer is at the surface). Light values of up to 200 W/m2 were recorded at 0.5 mm depth and up to 100 W/m2 at 1mm depth in the dry sandstone; rock moisture data showed that at this site the rock remained dry irrespective of atmospheric conditions. The light penetration means that there can be rapid and large subsurface thermal fluctuations contemporaneous with those at the rock surface, and that the thermal gradient is not as steep (approximately 1°C/mm in the surficial part of the rock) as where light‐to‐heat transfer is solely at the surface. Further, the presence of subsurface photosynthetically active radiation can (potentially) facilitate colonization by endolithic organisms. Here, as part of a study of the weathering of San rock art on sandstone in southern Africa, a first attempt is made to monitor the extent of light penetration and the resulting thermal conditions in the outer few millimeters of the sandstone. © 2009 Wiley Periodicals, Inc.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".