Chemostratigraphy of Cumberland Group (Pennsylvanian) strata influenced by salt tectonics, Joggins Fossil Cliffs UNESCO World Heritage Site, eastern Canada

ABSTRACT The Pennsylvanian stratigraphy of the western Cumberland Basin has been influenced by salt tectonics, specifically the formation of the Minudie Anticline, a salt wall. South of the Minudie Anticline, along the shoreline of the Joggins Fossil Cliffs UNESCO World Heritage Site, the post–Boss Point Formation succession comprises an ∼ 3 km succession of strata assigned to the Little River, Joggins, Springhill Mines, and Ragged Reef formations. North of the Minudie anticline, the Grande Anse Formation lies in angular unconformity on the Boss Point and basal Little River formations. Biostratigraphic studies have not been able to discern whether the Grande Anse Formation is equivalent to all, or just one, of the Joggins to Ragged Reef units south of the salt wall (the Minudie Anticline). To further investigate the relationship of the Grande Anse Formation with the units along the Joggins shoreline, forty sandstone samples from the post–Boss Point Fm strata were selected for a chemostratigraphic study, using inductively coupled plasma mass spectrometry (ICP-MS) to determine major-element compositions. Transformed ICP-MS data, subjected to a Kruskal-Wallis test and post-hoc tests, show that there is no significant difference between Grande Anse and Ragged Reef formations in the mean values of almost all analyzed elements. In contrast, there are significant differences when comparing these two units and the older Little River, Joggins, and Springhill Mines formations in the case of elements usually encountered in detrital mineral phases (Si, Al, Ti, Na, and Fe). Sandstones of the Grande Anse and Ragged Reef formations show greater compositional maturity than the Little River, Joggins, and Springhill Mines formations. This trend is explained by a gradual overall change in paleoclimate from semiarid conditions during deposition of the Little River Formation to humid conditions during deposition of the Grande Anse and Ragged Reef formations, causing greater chemical weathering of the sediment. These findings indicate that > 2 km of sediment (Little River, Joggins, and Springhill Mines formations) accumulated south of the salt wall during the major episode of salt diapirism, followed by erosion of any topographic high associated with the salt wall, and accumulation of a further > 500 m of sediment (the laterally equivalent Ragged Reef and Grand Anse formations), all within a timespan of only ∼ 2 Myr.

Stratigraphy and sedimentology of the Pennsylvanian Grande Anse Formation, Cumberland Basin, eastern Canada: its relationship to salt tectonics and coeval strata of the Joggins World Heritage Site

The Cumberland Basin is one of several sedimentary basins composing the late Paleozoic Maritimes Basin complex of eastern Canada. Pennsylvanian salt tectonics in the Cumberland Basin caused two salt mini-basins to evolve on either side of the Minudie Anticline, a salt wall. South of the wall (Athol Syncline), along the Joggins World Heritage shoreline, an ∼3000 m succession of strata (Little River, Joggins, Springhill Mines, and Ragged Reef formations) accumulated conformably on the Boss Point Formation. North of the wall (Black Point sub-basin), the biostratigraphically equivalent, but mostly unstudied, ∼600 m thick succession of Grande Anse Formation lies in angular unconformity on folded and faulted Boss Point and basal Little River formations. Grande Anse Formation sedimentology indicates four lithofacies associations: floodplain (LA1), braided channel (LA2), sheet flood (LA3), and debris flow deposits (LA4). One possible model has the Black Point sub-basin with its own hydrological system, completely separated from the Athol Syncline. A low subsidence rate combined with the low sedimentation rate produced the ∼600 m thick sand- and mud-prone succession that was contemporaneous with the ∼3 km succession to the south. The second model proposes that north of the salt wall was exposed to erosion during accumulation of Joggins and Springhill Mines formation strata to the south. Subsequently, the sediment of the lithologically similar Ragged Reef and Grande Anse formations either (i) onlapped to the north, unconformably on the folded Boss Point; or (ii) unconformably–disconformably on the underlying strata after a period of time indistinguishable in the biostratigraphic record.

Atrocity, Race, and Region in the Early Haitian Revolution: The Fond d’Icaque Rising

Set within a larger analysis of class relations in the Haitian Revolution, this is a microhistory that intersects with several important themes in the revolution: rumor, atrocity, the arming of slaves, race relations, and the origins and wealth of the free colored population. It is an empirical investigation of an obscure rebellion by free men of color in the Grande Anse region in 1791. Although the rebellion is obscure, it is associated with an atrocity story that has long resonated in discussion of the revolution. Formerly the least-known segment of Caribbean society, research has shed much new light on free people of color in recent decades, but much remains to be clarified. In certain ways, they are the key to understanding the Haitian Revolution, because of their anomalous position in Saint Domingue society and the way their activism precipitated its unraveling. The Grande Anse region had a unique experience of the revolution in that white supremacy and slavery were maintained there longer than in any other part of the colony. Based primarily on unexploited or little-known sources the article demonstrates the range and depth of research that remains possible and suggests that a regional focus is best way to advance current scholarship on the Haitian Revolution.

A technique to predict hourly potential solar radiation and temperature for a mostly unmonitored area in the Cape Breton Highlands

A technique was developed to obtain predictions of potential solar radiation and temperature for a prescribed, mostly unmonitored, area in the Cape Breton Highlands region of northeastern Nova Scotia (46°39′N 60°57′W to 46°40′N 60°24′W). Hourly predictions of incoming solar radiation are based on relations of sun-earth geometry, clear-sky atmospheric transmittance, and land-surface attributes resolved from digital terrain and vegetation models. The digital vegetation model characterizes vegetation cover and is used to define the average midday albedoes for the area in question. Hourly albedoes are calculated according to assigned mid-day albedo and sun-illumination angles. Land-surface characteristics (elevation, slope, aspect, horizon angles, terrain configuration factor, and view factor) affect total incident solar radiation by affecting the direct, diffused, and reflected energy components. Hourly spatial variability in above-ground daytime temperature is captured by way of a fully trained artificial neural network (ANN) that describes hourly fluctuations of interior highland temperatures according to i) reference temperatures taken at two lowland locations, one at Ingonish Beach and the other at Grande Anse; ii) distance from a north-south line representing the east coast of the study area and from the Grande Anse location; iii) time of day; and iv) land-surface attributes. Training the ANN involves supplying the network with actual data and having the network adjust its internal weights iteratively so that the output values are sufficiently close to the supplied target values. Comparison of predicted and observed hourly spring-summer (1997) temperatures revealed that the constructed ANN explained over 88% of the variability exhibited in the observed temperatures and that the standard error of estimate was 2.0 °C (mean absolute error = 1.5 °C). Key words: Sun-earth geometry, radiation laws, variable surface albedo, clear-sky atmospheric transmissivity, digital terrain, vegetation models, artificial neural networks

Repartition spatiale des contaminants dans les sediments du Lac St-Louis (Fleuve St-Laurent)

Les sédiments de 39 stations du lac St-Louis ont été échantillonnés et analysés pendant l'été 1984 pour la granulométrie, dix éléments majeurs et les contaminants (Ni, Co, Cr, V, Pb, Zn, Hg, As, HCB, pp'-DDE, Aroclor1242™, Aroclorl254™, Aroclorl260™). Dans la plupart des stations les teneurs sont plus élevées que les normes établies par le ministère de l'Environnement de l'Ontario pour le dépôt de déchets de dragage en eau libre. Avec ces données, nous avons réalisé des cartographies du lac, ce qui nous a permis de discerner trois zones où les teneurs en contaminants sont plus élevées : entre la baie de Valois (Dorval) et la Grande Anse (île Perrot), au sud des îles de la Paix (Beauharnois) et au sud de l'île Perrot (Anse au Sable). D'autre part, nous avons calculé des corrélations entre les variables, ce qui nous a permis de constater qu'il existe de fortes corrélations entre les métaux lourds et entre les contaminants organiques entre eux, mais beaucoup moins entre ces deux groupes de contaminants. Finalement, des méthodes statistiques multidimensionnelles ont été utilisées pour regrouper les stations en fonction de leur composition chimique, et cartographier le lac St-Louis. Il en ressort un groupe principal pour les éléments majeurs comprenant les 3 zones de sédimentation. Cependant, ces trois zones semblent avoir des caractéristiques différentes quant à leur composition en contaminants.