Premise of research. The Eocene fossil flora of the area around Vancouver, British Columbia is po... more Premise of research. The Eocene fossil flora of the area around Vancouver, British Columbia is poorly known despite work beginning in the 1890-1920s. The floristic character of the previously unstudied Burnaby Mountain flora from the Huntingdon Formation in British Columbia is reconstructed using plant megafossils and palynology. This site offers insight into the terrestrial vegetation and paleoclimate during the late middle to late Eocene of the Pacific Northwest of North America in a coastal setting during a global cooling trend. Methodology. Megaflora and microflora were identified, and the combined flora compared to that of coeval floras from northwestern Washington. Paleoclimate was reconstructed from leaf morphology using the Climate Leaf Analysis Multivariate Program, leaf margin analysis, and leaf area analysis. A probabilistic nearest living relative approach was used to reconstruct paleoclimate independently of leaf morphology, using taxonomic identifications from both mega-and microfossils. These data were combined in an ensemble approach. Pivotal results. The Burnaby Mountain fossil flora is late middle Eocene to late Eocene in age, and shares key plant taxa with the coeval Upper Ravenian flora of the Puget Group and the upper Chumstick Formation of northwestern Washington. The fossil flora contained a mix of subtropical and temperate forest elements, including rare palm and possible cycad leaf fragments, rare conifer pollen, and a diversity of broadleaf trees. Conclusions. The reconstructed paleoclimate suggests humid warm-temperate to marginally subtropical conditions in coastal British Columbia during the late middle Eocene to late Eocene. An ensemble paleoclimate approach provided a most-parsimonious mean annual temperature estimate of 16.2 ± 3.1 °C for the Burnaby Mountain fossils, and mean annual precipitation of 134 ± 56 cm. A modern climatic analogue is present on the east coast of the United States in North Carolina, where palms are part of the native flora.
Depositional evidence of Early Pleistocene glaciations in British Columbia are documented at only... more Depositional evidence of Early Pleistocene glaciations in British Columbia are documented at only a few sites. Near Kelowna, in southern British Columbia, a construction project exposed glacial sediments beneath Lambly Creek Basalt, providing a minimum age for this glaciation. The basalt is composed of a number of flows yielding ages that range from 0.76 ± 0.11 to 1.5 ± 0.1 Ma. The sediments consist of a diamicton, interpreted to be till, up to 3 m thick mantled by a weakly developed paleosol. The diamicton is underlain by fluvial sands up to 5 m thick, in places revealing injection features, and minor faulting. A unit of stratified gravel underlain by grey clay is inferred to underlie the exposed sediments, based on nearby outcrops and excavations. Sediments and overlying basalts are normally magnetized and are assigned to the Jaramillo normal subchron (1.069–0.987 Ma). The till is here referred to as the Westbank First Nation Till. It is Early Pleistocene in age and represents the...
High-resolution pollen analysis of laminated marine sediments from ODP Hole 1034B in Saanich Inle... more High-resolution pollen analysis of laminated marine sediments from ODP Hole 1034B in Saanich Inlet, British Columbia reveals changes in vegetation and inferred climate during the Holocene. Four main pollen zones are discerned using constrained cluster analysis. Although the timing of major vegetation changes at the Saanich Inlet is similar to other study sites in the Pacific Northwest, the composition of pollen assemblage zones is different from the mainland sites. Vegetation assemblages reconstructed from the pollen and spore record include a Douglas-fir (Pseudotsuga menziesii) parkland with abundant grass (Poaceae) and bracken (Pteridium) between 11,450 and 8300 BP (all ages are calibrated calendar years), oak (Quercus) savanna or parkland with high grass and bracken (8300-7040 BP), a mixed deciduous/coniferous forest with oak, western hemlock (Tsuga heterophylla) and Douglas-fir (7040-5750 BP), and the development of modern coastal temperate forest with the marked expansion of cedar (Cupressaceae), western hemlock, spruce (Picea) and Douglas-fir (5750-1050 BP). Climatic periods inferred from the cores include an early Holocene warm/dry interval (11,450-8300 BP), a warm period with mild winters (8300-7040 BP), a period of transitional mid-Holocene climate (7040-5750 BP), and the advent of a relatively cool/wet neoglacial climate after 5750 BP. Modern conifer forests and oak savannas became established by about 3800 BP. The Saanich Inlet pollen record indicates that vegetation and inferred climate change was particularly rapid between 8700 and 8300 BP when grass and bracken abruptly decrease and oak becomes a significant component of the paleovegetation. Because neoglacial conditions have prevailed from 3800 years to present in the Pacific Northwest, factors other than climate, such as anthropogenic modification of the landscape, may be responsible for the persistence of oak savannas.
Two anomalous, gray, silty clay beds are present in ODP cores collected from Saanich Inlet, Vanco... more Two anomalous, gray, silty clay beds are present in ODP cores collected from Saanich Inlet, Vancouver Island, British Columbia, Canada. The beds, which date to about 10,500 14C yr BP (11,000 calendar years BP), contain Tertiary pollen derived from sedimentary rocks found only in the Fraser Lowland, on the mainland of British Columbia and Washington just east of the Strait of Georgia. Abundant illite-muscovite in the sediments supports a Fraser Lowland provenance.The clay beds are probably distal deposits of huge floods that swept through the Fraser Lowland at the end of the Pleistocene. Muddy overflow plumes from these floods crossed the Strait of Georgia and entered Saanich Inlet, where the sediment settled from suspension and blanketed diatom-rich mud on the fiord floor. The likely source of the floods is Late Pleistocene, ice-dammed lakes in the Fraser and Thompson valleys, which are known to have drained at about the time the floods occurred.
Several birch bark containers and other birch bark artifacts made by prehistoric First Nations ha... more Several birch bark containers and other birch bark artifacts made by prehistoric First Nations have been encountered during archaeological excavations on the Canadian Plateau of British Columbia. From these discoveries, it is apparent that birch bark technologies were of major importance to First Nations, yet little attention has been paid to them as a category of artifacts. Ethnographic records from the Canadian Plateau indicate that birch bark basketry was consistently made by women. Thus, birch bark baskets provide a tool with which to make women and their work visible in the archaeological record. Birch bark baskets were important for food collection and storage, and appear in burials and girls puberty rituals. Here we describe two Late Period birch bark baskets and their contents (approximately dating to the Plateau Horizon 2400–1200 BP) from sites near Lillooet, BC and illustrate how birch bark was closely associated with women, both economically and spiritually.
We describe the Cephalozygoptera, a new, extinct suborder of Odonata, composed of the families Dy... more We describe the Cephalozygoptera, a new, extinct suborder of Odonata, composed of the families Dysagrionidae and Sieblosiidae, previously assigned to the Zygoptera, and possibly the Whetwhetaksidae n. fam. The Cephalozygoptera is close to the Zygoptera, but differs most notably by distinctive head morphology. It includes 59 to 64 species in at least 19 genera and one genus-level parataxon. One species is known from the Early Cretaceous (Congqingia rhora Zhang), possibly three from the Paleocene, and the rest from the early Eocene through late Miocene. We describe new taxa from the Ypresian Okanagan Highlands of British Columbia, Canada and Washington, United States of America: 16 new species of Dysagrionidae of the existing genus Dysagrion (D. pruettae); the new genera Okanagrion (O. threadgillae, O. hobani, O. beardi, O. lochmum, O. angustum, O. dorrellae, O. liquetoalatum, O. worleyae, all new species); Okanopteryx (O. jeppesenorum, O. fraseri, O. macabeensis, all new species); St...
Paleogene sediments of the Huntingdon Formation, a correlative to the Chuckanut Formation of neig... more Paleogene sediments of the Huntingdon Formation, a correlative to the Chuckanut Formation of neighboring Washington State, USA, are exposed in the greater Vancouver area, British Columbia, Canada. Palynology and plant macrofossils suggest the Kanaka Creek section is Paleocene rather than Eocene in age. Detrital zircon dating is less decisive, yet indicates the Kanaka rocks are no older than Maastrichtian. Analyses of plant macro- and microfossils suggest an early to middle Paleocene age for the Kanaka fossil flora. Paleocene indicators include macrofossils such as Platanus bella, Archeampelos, Hamamelites inequalis, and Ditaxocladus, and pollen taxa such as Paraalnipollenites, Triporopollenites mullensis, and Duplopollis. Paleogene taxa such as Woodwardia maxonii, Macclintockia, and Glyptostrobus dominate the flora. Fungal spores including the Late Cretaceous Pesavis parva and the Paleogene Pesavis tagluensis are notable age indicators. Physiognomy of 41 angiosperm leaf morphotypes ...
Plant macrofossil and pollen analyses of sediments from a high elevation lake on the Queen Charlo... more Plant macrofossil and pollen analyses of sediments from a high elevation lake on the Queen Charlotte Islands, British Columbia, reveal changes in vegetation and inferred climate during the Holocene. Pollen and macrofossil zones at Louise Pond correlate well during the early Holocene, showing that vegetation changes recorded in the fossil diagrams occurred near the lake basins. Paleobotanical evidence for local presence of western hemlock (Tsuga heterophylla [Raf.] Sarg. trees between ca 9 600 and 8 700 ± 150 yr BP indicates a warmer climate than today in the early Holocene. Declining western hemlock and increasing mountain hemlock (Tsuga mertensiana Bong.) fossils suggest some lowering of tree line at Louise Pond between about 8 700 ± 150 and ca 7 300 yr BP. Radiocarbon dates from Shangri-La Bog and SC-1 Pond (7 190 ± 100 yr BP and 7 180 ± 110 yr BP respectively) show that climatic deterioration was occurring regionally by this time on the Queen Charlotte Islands. The development of upper subalpine mountain hemlock forest similar to today began around 3 400 yr BP and may correspond with climatic deterioration that caused the Tiedemann glacial advance (3 300-1 900 yr BP) in the south-coastal mountains of British Columbia. Plant macrofossil analysis in small lakes is shown to be useful in interpreting vegetation shifts in subalpine areas where lowland pollen rain interferes with interpretation of the local palynological record.
Garry oak (Quercus garryana) ecosystems are listed as ''at-risk'' or endangered throughout their ... more Garry oak (Quercus garryana) ecosystems are listed as ''at-risk'' or endangered throughout their global range. In Canada, they are an umbrella for over one hundred species that are endangered to some degree. In order to effectively recover or allow these species to persist where possible, understanding of the ecological processes essential to their ongoing survival is needed. Fire suppression, aboriginal land-use, climate change, and post-colonial development have lead to drastic changes in the structure and amount of Garry oak ecosystems in North America. This paper presents new data using pollen and charcoal analysis to reconstruct past vegetation change and disturbance regimes for Garry oak and coastal Douglas-fir ecosystems over the past *500 years. Significant change in vegetation at the study sites has occurred with the greatest change in community structure and decline in Garry oak ecosystems occurring after the end of the Little Ice Age and as the impacts of western colonization occurred in the mid to late 19th century. Understanding mean fire return intervals (MFRI), ecosystem dynamics over time, and the role of people in this ecosystem structure is critical to the success of conservation efforts that are designed to ensure the long-term survival of these communities. The MFRI, inferred from charcoal analysis, ranges from 26 to 41 years on Vancouver and Pender Islands, Canada. Our results indicate that fire suppression, cessation of aboriginal land-use, climate change, western colonization and subsequent intensification of land-use has greatly altered Garry oak Communicated by Frank Chambers.
Rodent middens from ice-rich loess deposits are important new paleoenvironmental archives for Eas... more Rodent middens from ice-rich loess deposits are important new paleoenvironmental archives for Eastern Beringia. Plant macrofossils recovered from three middens associated with Dawson tephra (ca. 24,00014C yr B.P.) at two sites in Yukon Territory include diverse graminoids, forbs, and mosses. These data suggest substantial local scale floristic and habitat diversity in valley settings, including steppe-tundra on well-drained soils, moist streamside meadows, and hydric habitats. Fossil arctic ground squirrel burrows and nesting sites indicate that permafrost active layers were thicker during Pleistocene glacial periods than at present on north-facing slopes.
Analysis of the distributions of chironomid (midge) and other dipteran subfossils from two high e... more Analysis of the distributions of chironomid (midge) and other dipteran subfossils from two high elevation lake sediment cores in the Cascade Mountains reveals changes in midge communities and inferred climate since the late-glacial. Cabin Lake and 3M Pond are located near treeline in the subalpine Engelmann Spruce/Subalpine Fir biogeoclimatic zone of British Columbia. In Cabin Lake, chironomid head capsule assemblages depict a typical late-glacial community, and three distinct Holocene communities. In Cabin Lake, the late-glacial community is composed of cold-stenothermous taxa dominated by Stictochironomus, Mesocricotopus, Heterotrissocladius, Parakiefferiella nigra, Protanypus and Paracladius, whereas warm water midges are absent or rare, indicating cold conditions. A late-glacial chironomid community was not found in 3M Pond. In both lakes the early Holocene is dominated by a diverse warm-adapted assemblage, corresponding to the warm climatic conditions of the xerothermic period. Cabin Lake's mid-Holocene zone records a decrease in relative abundance of the warm water types and is accompanied by an increase in cold-stenotherms. At 3M Pond this period shows a dramatic loss in diversity of warm-adapted taxa, as the temperate genus Dicrotendipes dominates. This zone corresponds to Hebda's (1995) mesothermic period. Further cooling in the late Holocene (to modern conditions) is inferred from continued reduction of warm water midges and persistence (at Cabin Lake) or appearance (at 3M Pond) of a cold-stenothermal community. This late Holocene cooling is similar in timing to Neoglacial advances in the Coast, Cascade, and Rocky Mountains of southern British Columbia. Similarities in the timing of chironomid and vegetation community changes at these high elevation sites, along with the more rapid response time of the Chironomidae, support the sensitivity of midges to postglacial climatic change at high elevation sites.
Premise of research. The Eocene fossil flora of the area around Vancouver, British Columbia is po... more Premise of research. The Eocene fossil flora of the area around Vancouver, British Columbia is poorly known despite work beginning in the 1890-1920s. The floristic character of the previously unstudied Burnaby Mountain flora from the Huntingdon Formation in British Columbia is reconstructed using plant megafossils and palynology. This site offers insight into the terrestrial vegetation and paleoclimate during the late middle to late Eocene of the Pacific Northwest of North America in a coastal setting during a global cooling trend. Methodology. Megaflora and microflora were identified, and the combined flora compared to that of coeval floras from northwestern Washington. Paleoclimate was reconstructed from leaf morphology using the Climate Leaf Analysis Multivariate Program, leaf margin analysis, and leaf area analysis. A probabilistic nearest living relative approach was used to reconstruct paleoclimate independently of leaf morphology, using taxonomic identifications from both mega-and microfossils. These data were combined in an ensemble approach. Pivotal results. The Burnaby Mountain fossil flora is late middle Eocene to late Eocene in age, and shares key plant taxa with the coeval Upper Ravenian flora of the Puget Group and the upper Chumstick Formation of northwestern Washington. The fossil flora contained a mix of subtropical and temperate forest elements, including rare palm and possible cycad leaf fragments, rare conifer pollen, and a diversity of broadleaf trees. Conclusions. The reconstructed paleoclimate suggests humid warm-temperate to marginally subtropical conditions in coastal British Columbia during the late middle Eocene to late Eocene. An ensemble paleoclimate approach provided a most-parsimonious mean annual temperature estimate of 16.2 ± 3.1 °C for the Burnaby Mountain fossils, and mean annual precipitation of 134 ± 56 cm. A modern climatic analogue is present on the east coast of the United States in North Carolina, where palms are part of the native flora.
Depositional evidence of Early Pleistocene glaciations in British Columbia are documented at only... more Depositional evidence of Early Pleistocene glaciations in British Columbia are documented at only a few sites. Near Kelowna, in southern British Columbia, a construction project exposed glacial sediments beneath Lambly Creek Basalt, providing a minimum age for this glaciation. The basalt is composed of a number of flows yielding ages that range from 0.76 ± 0.11 to 1.5 ± 0.1 Ma. The sediments consist of a diamicton, interpreted to be till, up to 3 m thick mantled by a weakly developed paleosol. The diamicton is underlain by fluvial sands up to 5 m thick, in places revealing injection features, and minor faulting. A unit of stratified gravel underlain by grey clay is inferred to underlie the exposed sediments, based on nearby outcrops and excavations. Sediments and overlying basalts are normally magnetized and are assigned to the Jaramillo normal subchron (1.069–0.987 Ma). The till is here referred to as the Westbank First Nation Till. It is Early Pleistocene in age and represents the...
High-resolution pollen analysis of laminated marine sediments from ODP Hole 1034B in Saanich Inle... more High-resolution pollen analysis of laminated marine sediments from ODP Hole 1034B in Saanich Inlet, British Columbia reveals changes in vegetation and inferred climate during the Holocene. Four main pollen zones are discerned using constrained cluster analysis. Although the timing of major vegetation changes at the Saanich Inlet is similar to other study sites in the Pacific Northwest, the composition of pollen assemblage zones is different from the mainland sites. Vegetation assemblages reconstructed from the pollen and spore record include a Douglas-fir (Pseudotsuga menziesii) parkland with abundant grass (Poaceae) and bracken (Pteridium) between 11,450 and 8300 BP (all ages are calibrated calendar years), oak (Quercus) savanna or parkland with high grass and bracken (8300-7040 BP), a mixed deciduous/coniferous forest with oak, western hemlock (Tsuga heterophylla) and Douglas-fir (7040-5750 BP), and the development of modern coastal temperate forest with the marked expansion of cedar (Cupressaceae), western hemlock, spruce (Picea) and Douglas-fir (5750-1050 BP). Climatic periods inferred from the cores include an early Holocene warm/dry interval (11,450-8300 BP), a warm period with mild winters (8300-7040 BP), a period of transitional mid-Holocene climate (7040-5750 BP), and the advent of a relatively cool/wet neoglacial climate after 5750 BP. Modern conifer forests and oak savannas became established by about 3800 BP. The Saanich Inlet pollen record indicates that vegetation and inferred climate change was particularly rapid between 8700 and 8300 BP when grass and bracken abruptly decrease and oak becomes a significant component of the paleovegetation. Because neoglacial conditions have prevailed from 3800 years to present in the Pacific Northwest, factors other than climate, such as anthropogenic modification of the landscape, may be responsible for the persistence of oak savannas.
Two anomalous, gray, silty clay beds are present in ODP cores collected from Saanich Inlet, Vanco... more Two anomalous, gray, silty clay beds are present in ODP cores collected from Saanich Inlet, Vancouver Island, British Columbia, Canada. The beds, which date to about 10,500 14C yr BP (11,000 calendar years BP), contain Tertiary pollen derived from sedimentary rocks found only in the Fraser Lowland, on the mainland of British Columbia and Washington just east of the Strait of Georgia. Abundant illite-muscovite in the sediments supports a Fraser Lowland provenance.The clay beds are probably distal deposits of huge floods that swept through the Fraser Lowland at the end of the Pleistocene. Muddy overflow plumes from these floods crossed the Strait of Georgia and entered Saanich Inlet, where the sediment settled from suspension and blanketed diatom-rich mud on the fiord floor. The likely source of the floods is Late Pleistocene, ice-dammed lakes in the Fraser and Thompson valleys, which are known to have drained at about the time the floods occurred.
Several birch bark containers and other birch bark artifacts made by prehistoric First Nations ha... more Several birch bark containers and other birch bark artifacts made by prehistoric First Nations have been encountered during archaeological excavations on the Canadian Plateau of British Columbia. From these discoveries, it is apparent that birch bark technologies were of major importance to First Nations, yet little attention has been paid to them as a category of artifacts. Ethnographic records from the Canadian Plateau indicate that birch bark basketry was consistently made by women. Thus, birch bark baskets provide a tool with which to make women and their work visible in the archaeological record. Birch bark baskets were important for food collection and storage, and appear in burials and girls puberty rituals. Here we describe two Late Period birch bark baskets and their contents (approximately dating to the Plateau Horizon 2400–1200 BP) from sites near Lillooet, BC and illustrate how birch bark was closely associated with women, both economically and spiritually.
We describe the Cephalozygoptera, a new, extinct suborder of Odonata, composed of the families Dy... more We describe the Cephalozygoptera, a new, extinct suborder of Odonata, composed of the families Dysagrionidae and Sieblosiidae, previously assigned to the Zygoptera, and possibly the Whetwhetaksidae n. fam. The Cephalozygoptera is close to the Zygoptera, but differs most notably by distinctive head morphology. It includes 59 to 64 species in at least 19 genera and one genus-level parataxon. One species is known from the Early Cretaceous (Congqingia rhora Zhang), possibly three from the Paleocene, and the rest from the early Eocene through late Miocene. We describe new taxa from the Ypresian Okanagan Highlands of British Columbia, Canada and Washington, United States of America: 16 new species of Dysagrionidae of the existing genus Dysagrion (D. pruettae); the new genera Okanagrion (O. threadgillae, O. hobani, O. beardi, O. lochmum, O. angustum, O. dorrellae, O. liquetoalatum, O. worleyae, all new species); Okanopteryx (O. jeppesenorum, O. fraseri, O. macabeensis, all new species); St...
Paleogene sediments of the Huntingdon Formation, a correlative to the Chuckanut Formation of neig... more Paleogene sediments of the Huntingdon Formation, a correlative to the Chuckanut Formation of neighboring Washington State, USA, are exposed in the greater Vancouver area, British Columbia, Canada. Palynology and plant macrofossils suggest the Kanaka Creek section is Paleocene rather than Eocene in age. Detrital zircon dating is less decisive, yet indicates the Kanaka rocks are no older than Maastrichtian. Analyses of plant macro- and microfossils suggest an early to middle Paleocene age for the Kanaka fossil flora. Paleocene indicators include macrofossils such as Platanus bella, Archeampelos, Hamamelites inequalis, and Ditaxocladus, and pollen taxa such as Paraalnipollenites, Triporopollenites mullensis, and Duplopollis. Paleogene taxa such as Woodwardia maxonii, Macclintockia, and Glyptostrobus dominate the flora. Fungal spores including the Late Cretaceous Pesavis parva and the Paleogene Pesavis tagluensis are notable age indicators. Physiognomy of 41 angiosperm leaf morphotypes ...
Plant macrofossil and pollen analyses of sediments from a high elevation lake on the Queen Charlo... more Plant macrofossil and pollen analyses of sediments from a high elevation lake on the Queen Charlotte Islands, British Columbia, reveal changes in vegetation and inferred climate during the Holocene. Pollen and macrofossil zones at Louise Pond correlate well during the early Holocene, showing that vegetation changes recorded in the fossil diagrams occurred near the lake basins. Paleobotanical evidence for local presence of western hemlock (Tsuga heterophylla [Raf.] Sarg. trees between ca 9 600 and 8 700 ± 150 yr BP indicates a warmer climate than today in the early Holocene. Declining western hemlock and increasing mountain hemlock (Tsuga mertensiana Bong.) fossils suggest some lowering of tree line at Louise Pond between about 8 700 ± 150 and ca 7 300 yr BP. Radiocarbon dates from Shangri-La Bog and SC-1 Pond (7 190 ± 100 yr BP and 7 180 ± 110 yr BP respectively) show that climatic deterioration was occurring regionally by this time on the Queen Charlotte Islands. The development of upper subalpine mountain hemlock forest similar to today began around 3 400 yr BP and may correspond with climatic deterioration that caused the Tiedemann glacial advance (3 300-1 900 yr BP) in the south-coastal mountains of British Columbia. Plant macrofossil analysis in small lakes is shown to be useful in interpreting vegetation shifts in subalpine areas where lowland pollen rain interferes with interpretation of the local palynological record.
Garry oak (Quercus garryana) ecosystems are listed as ''at-risk'' or endangered throughout their ... more Garry oak (Quercus garryana) ecosystems are listed as ''at-risk'' or endangered throughout their global range. In Canada, they are an umbrella for over one hundred species that are endangered to some degree. In order to effectively recover or allow these species to persist where possible, understanding of the ecological processes essential to their ongoing survival is needed. Fire suppression, aboriginal land-use, climate change, and post-colonial development have lead to drastic changes in the structure and amount of Garry oak ecosystems in North America. This paper presents new data using pollen and charcoal analysis to reconstruct past vegetation change and disturbance regimes for Garry oak and coastal Douglas-fir ecosystems over the past *500 years. Significant change in vegetation at the study sites has occurred with the greatest change in community structure and decline in Garry oak ecosystems occurring after the end of the Little Ice Age and as the impacts of western colonization occurred in the mid to late 19th century. Understanding mean fire return intervals (MFRI), ecosystem dynamics over time, and the role of people in this ecosystem structure is critical to the success of conservation efforts that are designed to ensure the long-term survival of these communities. The MFRI, inferred from charcoal analysis, ranges from 26 to 41 years on Vancouver and Pender Islands, Canada. Our results indicate that fire suppression, cessation of aboriginal land-use, climate change, western colonization and subsequent intensification of land-use has greatly altered Garry oak Communicated by Frank Chambers.
Rodent middens from ice-rich loess deposits are important new paleoenvironmental archives for Eas... more Rodent middens from ice-rich loess deposits are important new paleoenvironmental archives for Eastern Beringia. Plant macrofossils recovered from three middens associated with Dawson tephra (ca. 24,00014C yr B.P.) at two sites in Yukon Territory include diverse graminoids, forbs, and mosses. These data suggest substantial local scale floristic and habitat diversity in valley settings, including steppe-tundra on well-drained soils, moist streamside meadows, and hydric habitats. Fossil arctic ground squirrel burrows and nesting sites indicate that permafrost active layers were thicker during Pleistocene glacial periods than at present on north-facing slopes.
Analysis of the distributions of chironomid (midge) and other dipteran subfossils from two high e... more Analysis of the distributions of chironomid (midge) and other dipteran subfossils from two high elevation lake sediment cores in the Cascade Mountains reveals changes in midge communities and inferred climate since the late-glacial. Cabin Lake and 3M Pond are located near treeline in the subalpine Engelmann Spruce/Subalpine Fir biogeoclimatic zone of British Columbia. In Cabin Lake, chironomid head capsule assemblages depict a typical late-glacial community, and three distinct Holocene communities. In Cabin Lake, the late-glacial community is composed of cold-stenothermous taxa dominated by Stictochironomus, Mesocricotopus, Heterotrissocladius, Parakiefferiella nigra, Protanypus and Paracladius, whereas warm water midges are absent or rare, indicating cold conditions. A late-glacial chironomid community was not found in 3M Pond. In both lakes the early Holocene is dominated by a diverse warm-adapted assemblage, corresponding to the warm climatic conditions of the xerothermic period. Cabin Lake's mid-Holocene zone records a decrease in relative abundance of the warm water types and is accompanied by an increase in cold-stenotherms. At 3M Pond this period shows a dramatic loss in diversity of warm-adapted taxa, as the temperate genus Dicrotendipes dominates. This zone corresponds to Hebda's (1995) mesothermic period. Further cooling in the late Holocene (to modern conditions) is inferred from continued reduction of warm water midges and persistence (at Cabin Lake) or appearance (at 3M Pond) of a cold-stenothermal community. This late Holocene cooling is similar in timing to Neoglacial advances in the Coast, Cascade, and Rocky Mountains of southern British Columbia. Similarities in the timing of chironomid and vegetation community changes at these high elevation sites, along with the more rapid response time of the Chironomidae, support the sensitivity of midges to postglacial climatic change at high elevation sites.
Several birch bark containers and other birch bark artifacts made by precontact First Nations ha... more Several birch bark containers and other birch bark artifacts made by precontact First Nations have been encountered during archaeological excavations on the Canadian Plateau of British Columbia. From these discoveries, it is apparent that birch bark technologies were of major importance to First Nations, yet little attention has been paid to them as a category of artifacts. A unique collection of 923 birch bark artifacts excavated from eighteen Canadian Plateau sites in British Columbia from 1969–1976 were examined by the authors as part of previous paleoethnobotanical study (Table 1; Croft, N.d.; Mathewes 1980). Based on artifact form, three general classes were delineated in the paleoethnobotanical collection: baskets, rolled birch bark, and bark strips/sheets. We chose to focus on the baskets here for three reasons, 1) the significance of birch bark basketry is not yet well understood, 2) there is good evidence of birch bark basket use in both utilitarian and ritual contexts, and 3) birch bark basketry is an example of a technology identified with women.
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Papers by Rolf Mathewes