Evidence for late‐Pleistocene permafrost in the New Jersey Pine Barrens (latitude 39°N), eastern USA
Bibliographic record
Abstract
Abstract Relict sand wedges, up to 2.5 m deep and 0.4 m wide, are present in the Pine Barrens of southern New Jersey. They indicate the previous existence of permafrost. The wedges are composed predominantly of sand that shows evidence of wind transport and abrasion. Optically‐stimulated‐luminescence dating of infill material indicates that thermal‐contraction‐cracking and emplacement of the sand infill must have occurred during two separate periods during the Late Pleistocene. The most recent was in Late Wisconsinan times,∼15–18 ka. An earlier period of permafrost conditions is indicated by dates >55–65 ka. On both occasions, the Late‐Pleistocene ice sheets would have advanced as far south as northern New Jersey and strong winds would have occurred in the lower mid‐latitudes. The sandy soils of the Pine Barrens would have allowed the ice‐marginal periglacial zone to extend southwards into southern New Jersey. The sparse tundra vegetation on the sandy substrate, with its relatively high thermal conductivity, would have permitted deep frost penetration because the ‘thermal offset’ would have been minimized. A mean annual air temperature of between −3.0°C and −4.0°C is inferred. Permafrost was probably discontinuous and less than 10–15 m in thickness. Episodes of permafrost thaw are indicated by the widespread occurrence of deformed sediments (‘thermokarst involutions’) and by various small‐scale non‐diastrophic structures associated with bog ironstone beds. The presence of soil (ground) wedges in southern New Jersey and adjacent Delaware also suggest conditions of deep seasonal frost, probably when the most recent permafrost degraded. Copyright © 2003 John Wiley & Sons, Ltd.
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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) | 0.002 | 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".