A new interpretation for formation of orthogonal joints in quartz sandstone
Bibliographic record
Abstract
Two vertical and orthogonal systematic joint sets are generally arrayed in a grid pattern on the bedding surface, which are the significant features of flat-lying sandstone terrains. Although extensive researches are reported on this topic, many fundamental problems have still not been solved. Such mutually perpendicular opening-mode fractures are an obvious manifestation of effective tensile stresses in two orthogonal directions in the horizontal bedding plane. A good understanding of these orthogonal joint systems is a key to structural analysis, landscape interpretation, and guidance of resolving a number of very practical problems in engineering, mining and hydrologic projects. Based on an anatomic investigation on the orthogonal joints in the Potsdam sandstone of Cambrian age at Ausable Chasm (New York State, USA) and Beauharnois (Quebec, Canada), we proposed that the orthogonal joints may result from the auxetic effects of quartz-rich sandstone rather than local or regional rotation of the maximum tensile stress (σ3) direction by about 90°. The sandstone beds with negative Poisson's ratios are so fascinating that, when placed under vertical burial compression and layer-parallel extension in one direction (σ3), it becomes stretched in the transverse direction (σ2), producing two orthogonal sets of mutual abutting and intersecting joints (J1 and J2 normal to σ3 and σ2, respectively), and both are normal to the bedding surface. Joint set J1 is more closely-spaced than J2 by a factor of ∼3.3, which is correlated with an average Poisson's ratio of −0.3 for the Potsdam sandstone at the time of joint formation.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.005 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.010 | 0.001 |
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".