Quaternary geology of Long Island (Bahamas): an alternative perception of Bahamian island formation and relative sea-level changes in this area during the Last Interglacial
Bibliographic record
Abstract
Relying on a multi-method approach including morphostratigraphy, sedimentology, petrology, and Sr-isotope, U-Th, amino-acid racemization and 14 C dating, we have identified, described, and mapped eight allostratigraphic units on Long Island (NE Bahamas). These units mostly consist of eolianites, but locally include reefal and sandy coastal deposits. They range in age from the middle Pleistocene to the late Holocene, are usually separated by terra-rossa paleosols, and can generally be correlated with the members and formations previously defined on other Bahamian islands. However, the Buckley Settlement and the Dean's Bay units, respectively equivalents of the mid-Holocene North Point Member and of the late Pleistocene Whale Point Formation, are more widespread on Long Island than on other islands, possibly due to a difference in the width of the windward shelf. Furthermore, we could not identify on Long Island a counterpart of the French Bay Member, an extensive rock body supposedly accumulated during the transgression at the onset of the last interglacial period (LIG). The lack of such deposits brings about questions about the volume and the nature of transgressive sediments that can possibly be preserved during a sea-level cycle in the Bahamas, and leads us to reconsider previously proposed models of Bahamian island development. Finally, the examination and, in some cases, the dating of paleo sea-level markers of LIG age suggest that RSL on Long Island was about +3 m above modern datum in the first half of the LIG, and rose to about +5 m in the middle of this period. This rise was likely not preceded by an exposure event. • First geological map of Long Island, Bahamas from remote sensing and ground truth data. • Eight units from middle Pleistocene (MIS 13) to late Holocene identified and documented. • Transgressive French Bay Member absent, leading to reevaluation of Bahamian stratigraphic framework. • Two phases of reef growth were identified for the MIS 5e dated at 122.9 and 119.2 ka BP by U-Th dating. • Sea level markers show a RSL at +3 m in early MIS 5e and +5 m in mid-5e, no evidence of exposure between the two phases.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".