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Record W47469094 · doi:10.3406/barb.2007.28635

La formation des lithalses et leur croissance latérale

2007· article· en· W47469094 on OpenAlexaboutno aff
Albert Pissart

Bibliographic record

VenueBulletin de la Classe des sciences · 2007
Typearticle
Languageen
FieldEarth and Planetary Sciences
TopicClimate change and permafrost
Canadian institutionsnot available
Fundersnot available
KeywordsPermafrostGeologyAggradationThermokarstGeomorphologyErosionFrost heaving

Abstract

fetched live from OpenAlex

The lithalsas that occur in Hudsonie, northern Québec, Canada, are modern-day analogues to the features that formed the shallow depressions ('viviers') that occur today on the Hautes Fagnes, Belgium. Observations made in the two regions are complementary. They demonstrate that these periglacial mounds form first by vertical upheaving and later by lateral enlargment. The main observations in favour of this thesis are : 1) the regular morphology, either cicular or oval, of both actual lithalsas and traces of previous lithalsas, cannot be explained by simple vertical heave ; 2) the lateral extension of lithalsas, inferred from relict forms in the Hautes Fagnes, is clearly evident ; 3) the ramparts cannot be explained in terms of simple erosion of the lithalsa surface and subsequent lateral downslope movement of material under gravity to form the ramparts because (a) very low slope angles are involved and (b) thermokarst activity would have been initiated by the erosion ; 4) the oblique inclination of ice lenses observed within a lithalsa in Hudsonie indicates that the freezing plane (i.e. top of permafrost) was lateral, on the sides. In permafrost regions today, aggradational ice forms by segregation at the permafrost table. If the latter is inclined, the growth of aggradational ice can heave material both upwards and laterally. Therefore, enlargement of a lithalsa, and the preservation of its ramparts following thaw degradation, are thought to be associated with the growth of aggradational ice on the inclined permafrost table that surrounds the mound. This process is called "frost thrusting". The snow accumulations on the border of the lithalses explain the direction of advance of the freezing front. Calculation of the possible pressures developed by the growth of segregated ice supports this thesis. Figure 14 illustrates how lithalsas are thought to form. This explanation has to be verified in the arctic permafrost region of northern Quebec by excavating sections through actual lithalsas using a portable high pressure water pump.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.

How this classification was reachedexpand

Full frame machine prediction

Teacher imitation

Not 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.

metaresearch head score (Codex)0.001
metaresearch head score (Gemma)0.001
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.116
Threshold uncertainty score0.231

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0010.001
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.001
Bibliometrics0.0010.000
Science and technology studies0.0010.003
Scholarly communication0.0030.001
Open science0.0010.001
Research integrity0.0000.001
Insufficient payload (model declined to judge)0.0060.002

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.

Opus teacher head0.080
GPT teacher head0.314
Teacher spread0.234 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designObservational
Domainnot available
GenreEmpirical

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".

Quick stats

Citations1
Published2007
Admission routes1
Has abstractyes

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