The Adamstown Submergence Event: Faunal and Sedimentological Record of a Late Cambrian (Furongian) Transgression in the Appalachian Region
Bibliographic record
Abstract
The base of the Adamstown Member of the Frederick Formation, a thick succession of slope and basin-floor facies in Maryland, records flooding of the Appalachian shelf along the southern margin of Laurentia by a third- or fourth-order sea level rise in the middle Furongian (medial late Cambrian), a transgression here designated the Adamstown Submergence Event (ASE). Trilobites recently recovered from a coarse grainstone at the top of the underlying Rocky Springs Station Member, a thick lowstand systems tract deposited during the drawdown(s) that preceded the ASE, allow precise correlation with age-equivalent horizons in coeval slope deposits in Newfoundland, platform deposits in eastern New York State, and the immediately adjacent, cyclic peritidal platform-margin succession only tens of kilometers to the west in Maryland. Together with new trilobite and conodont data from the Thrombolite III interval in the Conococheague Formation, the fauna from the top of the Rocky Springs Station Member dates the ASE as most likely a latest Early Sunwaptan event that occurred during deposition of the highest beds of the Saratogia Zone in the platform succession, although an earliest Late Sunwaptan (basal Saukia Zone) age cannot be ruled out. Several of the species described here from the Frederick and Conococheague Formations have not previously been reported from the central Appalachians or anywhere else in eastern North America. The widespread, regional signature of the ASE in both the deep water and platform successions along the length of the Appalachians suggests a eustatic cause and excellent potential for recognition in other sedimentary basins both within and outside Laurentia. The new biostratigraphic data establish that the ASE occurred during deposition of strata near the middle of the Iverian Stage in Australia, within global Stage 9 of the international Cambrian time scale. Published sea level curves for this time interval include no eustatic, third order sea level rise, indicating that either these curves require revision, or the ASE was smaller in scale (fourth-order) and/or a product of regional tectonics, rather than eustasy.
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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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".