Great Canadian Lagerstätten 1. Early Eocene Lagerstätten of the Okanagan Highlands (British Columbia and Washington State)

The Early Eocene Okanagan High lands series of lacustrine shale and coal deposits, in far western North Ameri ca, constitutes a significant group of fossil sites with exceptional preserva tion of a diverse suite of organisms (Lagerstätten). With contemporaneous basins arrayed across about 1000 kilo metres of southern British Columbia and northern Washington, these sites offer a unique opportunity to examine the paleoecology of terrestrial commu nities spanning a temperate, low-sea sonality landscape in a montane setting during a time of generally warm tem peratures across the globe. The Okana gan Highlands sites provide an unpar alleled comparative framework within which to examine this major turning point in terrestrial community develop ment during the emergence of their broad modern character.La série de dépôts lacustres de schiste et de charbon du début de l’Éocène des hautes terres d’Okanagan, aux con fins de l’ouest de l’Amérique du Nord, constituent un groupe important de sites fossiles particulièrement bien con servés de suites d’organismes diverses (Lagerstätten). De nos jours, ces sites forment en une bande d’environ 1 000 kilomètres, depuis le sud de la Colom bie-Britannique jusqu’au nord de l’État de Washington. Dans le contexte de réchauffement climatique, c’est l’occa sion ou jamais d’étudier la paléoécolo gie de communautés terrestres dans des conditions climatiques modérées dans un paysage de montagne à faible saisonnalité. Les sites des hautes terres d’Okanagan représentent un cadre de comparaison sans pareil permettant d’étudier les effets de ce tournant majeur sur le développement des prin cipales caractéristiques modernes de la communauté terrestre

LATE-QUATERNARY FOSSIL CHIRONOMIDAE (DIPTERA) FROM HIPPA LAKE, QUEEN CHARLOTTE ISLANDS, BRITISH COLUMBIA, WITH SPECIAL REFERENCE TO<i>CORYNOCERA</i>ZETT.

AbstractChironomid stratigraphic analyses of sediment from Hippa Lake, Queen Charlotte Islands, B.C., revealed a fossil chironomid record unlike that reported for deeper lakes of southwestern British Columbia, but similar to an arctic Alaskan sequence. Little evidence of trophic succession or climatic change was noted.Chironomids, includingCorynoceranr.ambiguaZett., rapidly colonized the lake. Because the known adults ofCorynoceraZett. are brachypterous, the early arrival ofC. nr.ambiguaat Hippa Lake suggested either that this species survived in a Queen Charlotte glacial refugium, that chironomids can disperse very rapidly, even without active flight, or the existence of a previously undescribedCorynoceraspecies with well-developed wings.Elsewhere, fossils of theC.ambiguagroup are commonly associated with fossil oospores ofCharaValliant andNitellaAgardh. North American records are inconsistent, although similar correlations existed in some coastal lakes of British Columbia.</jats:p

Palynology and Paleoecology of Postglacial Sediments from the Lower Fraser River Canyon of British Columbia

The postglacial history of vegetation in the Yale area of the lower Fraser River Canyon is described from sediments of two lakes using percentage pollen analysis supplemented with macrofossil evidence and radiocarbon dating. Deposition of postglacial sediments, ranging from basal clays to gyttjas, began about 11 500 y B.P. Three distinct pollen assemblage zones are distinguished, reflecting in part the main climatic conditions for the intervals. The oldest zone, with high percentages of pine (Pinus) and alder (Alnus) pollen, suggests cool and moist conditions following withdrawal of glacial ice. This is followed by marked increases in Douglas-fir (Pseudotsuga), grasses and other nonarboreal pollen, suggesting in part, warmer and drier conditions. The third zone, ranging from about the Mt. Mazama ash at 6600 y B.P. to the present, is marked by high alder and Douglas-fir, and increasing cedar (Thuja-Chamaecyparis type), western hemlock (Tsuga heterophylla), fir (Abies) and birch; an assemblage indicating a return to wetter conditions. This sequence contrasts with previously described successions that recognized the classical Hypsithermal in adjacent areas. The sequence of inferred vegetational changes, although similar to those described for the Haney area to the west, suggests that the Yale area has been a biogeoclimatically transitional area for much of postglacial time. </jats:p