Daryl W. Fedje

Drowned forests and archaeology on the continental shelf of British Columbia, Canada

We have used high-resolution digital terrain imaging and sea-floor sampling to reveal drowned late glacial to early postglacial terrestrial landscapes at water depths as great as 150 m. In situ tree stumps and shellfish-rich paleobeaches are present on these drowned landscapes. A stone tool encrusted with barnacles and bryozoa was recovered from a drowned delta flood plain now 53 m below mean sea level. This is the first tangible evidence that the formerly subaerial broad banks of the western North American Continental Shelf may have been occupied by humans in earliest Holocene and possibly late-glacial time. Analyses ( 14 C) of the drowned terrestrial and intertidal deposits were used to refine the local sea-level curve, which shows very rapid change within this glacio-isostatically dynamic region.

Post glacial sea levels on the Western Canadian continental shelf: evidence for rapid change, extensive subaerial exposure, and early human habitation

Grounded piedmont type glaciers inundated and isostatically loaded the deep troughs which indent the Western Canadian continental shelf, as far west as the shelf edge. Glaciers do not appear to have covered the offshore banks east of the Queen Charlotte Islands (Haida Gwaii). Ice retreated from the shelf at approximately 13,500 14C yr B.P. Rapid emergence of the crust followed the ice retreat and resulted in a relative fall of sea level. At 10,400 14C yr B.P. relative sea level on the continental shelf was more than 100 m below that of today and large areas of the Queen Charlotte Basin were subaerially exposed. Eustatic sea-level rise, coupled with subsidence of a glacioisostatic forebulge, allowed sea levels to rise very rapidly, and reach the present shoreline on the Queen Charlotte Islands (Haida Gwaii) by about 9100 14C yr B.P. Dated shoreline deposits (shells), submerged wood remnants, and barnacles on stone tools at elevations between −110 m and +14 m suggest a sea-level rise of 6.3 cm per year between 12,200 and 11,000 calender years. Our reconstructions of the paleogeography and paleoenvironments suggest a hospitable environment for human habitation existed in areas that are now submerged. Stone tools excavated from intertidal deposits support this interpretation. Significant local variations in the depth of synchronous shorelines are described and attributed to localized differences in isostatic load. The documented rates of crustal adjustment are much greater than those used in conventional geophysical (forebulge) models. Regional high-resolution seismic reflection data (3400 line km) shows little evidence for post-glacial faulting and suggest that most crustal adjustments appear to have been isostatically rather than tectonically driven. Subaerial exposure and subsequent sea-level transgression were the dominant post-glacial processes that determined the morphology, texture and paleoenvironment of the Western Canadian continental shelf.

Modeling Paleoshorelines and Locating Early Holocene Coastal Sites in Haida Gwaii

The integration of archaeology and paleoecology has allowed a fuller understanding of the history of southern Haida Gwaii and provided insights into the regional history of coastal occupation in northwestern North America. Of particular consequence is the history of sea-level fluctuations during the late-glacial and early Holocene. The modern shore holds only part of the history of coastal occupation. Much is flooded or hidden in the rainforest. In southern Haida Gwaii, shorelines dating from 13,000 to 9,500 B.P. are deeply drowned while those dating from 9,200 to 3,000 B.P. are stranded in the rainforest up to 15 meters above modern levels. Shorelines have been approximately coincident with the current position for only the last two to three millennia and for a century or two centered around 9,400 B.P.. Modeling these paleoshorelines has led to discovery and investigation of a number of early Holocene archaeological sites.

Paleoecology of late-glacial terrestrial deposits with in situ conifers from the submerged continental shelf of western canada

Extensive portions of the continental shelf off the coast of British Columbia were subaerially exposed during Late Wisconsinan deglaciation due to lowering of relative sea level by as much as 150 m. Paleoecological analyses were conducted at two sites on the emergent continental shelf where terrestrial surfaces with in situ conifers are preserved. The woody plant remains confirm that, during the latest period of subaerial exposure, terrestrial vegetation was established on the continental shelf. Microscopic identification of fossil wood, and analyses of pollen and plant macrofossils from the associated paleosols and overlying shallow pond sediments indicate that productive Pinus contorta-dominated communities with abundant Alnus crispa and ferns grew on the shelf adjacent to and on the Queen Charlotte Islands around 12,200 14C yr B.P. Dwarf shrubs including Salix and Empetrum, and herbaceous plants such as Heracleum lanatum and Hippuris vulgaris, were also important components of the shelf vegetation. Near northern Vancouver Island, mixed coniferous forests dominated by Pinus contorta with Picea, Tsuga spp., Alnus spp., and ferns occupied the shelf at 10,500 14C yr B.P.

Early Environments and Archaeology of Coastal British Columbia

Coastal British Columbia is largely a rugged fjord-land archipelago. It has not always been so – over time, the coastline has changed configuration dramatically and the fauna and flora have seen multiple successions and extirpations. Through this, for the last 11,000 RCYBP years at least, resilient people made their living from the ocean and the land, shrugging off or taking advantage of environmental change. Similarly, archaeologists have worked the nooks and crannies of the coast for decades, surveying in the dense forest and digging in the deep middens, subject to similar environmental conditions as those they study and making quiet progress in regional culture histories. In more recent years, this area has been thrust to the forefront of research into the First Peopling of the American continents. As the Clovis First model began to be questioned, alternate modes and routes for the arrival of humans were brought in from the sidelines, including the hypothesized west coast route (e.g. Fladmark 1979). Not much research had been focused on this route, perhaps as Easton (1992) suggests, because of the terrestrial mindset of many archaeologists. Perhaps also, the prospects of finding sites on the deeply drowned landscapes or in the rugged, heavily forested hinterland was prohibitively daunting and led to a pessimistic outlook on success.