Winter weathering of fractured sedimentary rocks in a temperate climate: observation of freeze–thaw and thermal processes on the Niagara Escarpment, Hamilton, Ontario
Bibliographic record
Abstract
Abstract The Niagara Escarpment is a fractured Palaeozoic sedimentary cuesta, subject to year-round weathering in a temperate climate. We examined the temperature of the rock surface and fractures at three in situ sites with varying aspect and lithology, as well as the surface and interior of three control blocks maintained in outdoor conditions between December 2020 and March 2021. The objectives were to examine the interplay between freeze–thaw and thermal weathering in the winter months and to identify potential factors influencing these processes. Both diurnal-scale and prolonged freeze–thaw cycles differing in spatial and temporal extent were identified, coincident with periods of high moisture. We frequently observed rapid temperature changes (>1 °C min −1 ) at sites with strong insolation, which implies that the temperature regime is suitable for thermal shock and fatigue to occur. Site-specific factors, such as the aspect of the escarpment face and lithology, impact the mechanism and extent of weathering. Southeast-facing sites with high insolation are dominated by diurnal-scale freeze–thaw; west- and east-facing sites with lower insolation experience a more prominent prolonged freeze–thaw cycle. Across all sites there is a gradient between surface and fracture temperature that follows diurnal trends in air temperature and insolation. Variability in the surface-fracture gradient may enhance weathering processes by shifting the orientation and magnitude of stress, and by changing the spatial distribution of freezing and thawing. Our research indicates that site-specific factors and pre-existing fractures moderate the influence of air temperature and insolation on thermal gradients, and ultimately the weathering regime.
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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) | 0.015 | 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".