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The Geoarchaeological Setting of the Sebasticook Lake Fish Weir Newport, Maine
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A geophysical and coring survey of Sebasticook Lake, Newport, Maine, provides evidence of past human-landscape interactions associated with construction and use of a Middle Archaic to Middle Woodland period fish weir, located at the lake inlet. Geophysical methods employed included Seismic Reflection Profiling (SRP) and Sidescan Sonar (SSS) survey of the Sebasticook Lake basin, and Ground Penetrating Radar (GPR) survey of the fish weir site and lake inlet. Three cores were collected using a modified, square-rod Wright piston corer in the lake basin. The Sebasticook fish weir complex consists of >630 stone-tool-modified wooden stakes, driven into stiff underlying glacial mud at the lake inlet. The stakes were presumably connected by wattle or fencing to create a barrier to corral migrating anadromous and/or catadromous fish. Radiocarbon dating of the weir stakes suggests four possible periods of construction: 5820 + 60 BP to 4950 + 80 BP, 3990 + 80 BP to 3780 + 70 BP, 2940 + 70 BP to 2590 + 70 BP, and 1780 + 80 BP to 1560 + 60 BP. The range of dates makes the Sebasticook fish weir one of, if not the earliest, dated fish weirs in North America. The present study focused on three research areas: glacial and deglacial history of the lake basin, Holocene geology and lake-level change, and geoarchaeological site-formation processes of the fish weir inlet. Several submerged glacial features were identified by SRP and SSS surveys in the lake basin, including an esker segment, kame and kettle topography, and a moraine. Basin stratigraphy suggests that following deglaciation, Sebasticook Lake transitioned as an isolation basin from a glaciomarine to a glaciolacustrine environment before reaching its present geological and sedimentological configuration by ~10,000 BP. SRP and SSS survey and coring identified submerged erosional features and wetland deposits associated with a lake-level low-stand of ~9 m below present lake level (PLL) from 7860 BP to 6100 BP. During the low stand, Sebasticook Lake lowered below its outlet, forming a closed basin that was bisected by the esker segment. This study attempts to place this event within a context of regional lake-level and climate change and proposes a hypothesis to explain variability of lake-level records across northern New England and adjacent Canadian provinces. A GPR survey combined with a previous vibracoring study and a preliminary SRP survey identified two incised and infilled paleochannels at the lake inlet. Incision of the first, northern paleochannel was most likely related to lowering base level associated with the lake-level low stand. By 6100 BP, lake level had reached near-modern levels, opening the lake to the larger Kennebec River drainage and connecting the Sebasticook Lake and River to anadromous and catadromous fish runs. Construction of the fish weir at the inlet began shortly after this, by 5820 BP, and centered across the incised northern channel. Construction of the weir promoted sedimentation and infilling of the channel with organic detritus, causing the channel to migrate south. At some point between 2590 BP and 1780 BP, the anthropogenically-induced infilling caused the channel to avulse south, incising the identified southern channel. The northern channel was then abandoned, and humans continued weir construction within the newer, southern paleochannel, until the weir was completely abandoned sometime after 1560 BP.
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... McDowell-Loudan, State University of New York College at Cortland, personal communication) on a tributary of the Susquehanna River where remnants of more stone weirs are still visible in low water (Dohne 2004). In addition, sharpened wooden stakes in Maine's Sebasticiook Lake fish weir in the Kennebec River watershed, where eels were abundant, have been dated to between 5,800 and 1,700 years old (Miller et al. 2006). ...
We examine historical, archaeological, and current patterns in American eel
Anguilla rostrata use, abundance, and distribution to improve understanding of current pop- ulation-level status. Our research indicates that distribution and abundance has changed sig- nificantly in response to the cumulative impacts of fishing, turbine mortality, and major loss of freshwater habitat. The 1950–1970 peaks in dam construction and turbine mortalities, together with the unprecedented North American harvests in the 1970s, have lead to a peril- ous synergy of effects at the population level. Based on our findings, we call for coordinated conservation and management actions for American eel across North America. Preservation of life cycle diversity and coordinated conservation actions are required across the range to ensure continued and improved societal benefits, protect the legacy of cultural and natural heritage values, restore ecological services, and reinstate the benefits to biodiversity provided by this unique and important species. Finally, we describe key elements and recent progress in recovery planning.
Este artículo expone lo que sabemos hasta el momento sobre corrales de pesca en el mar interior de Chiloé (sur de Chile) tanto insular como continental (provincias de Llanquihue, Chiloé y
Palena). El mayor énfasis está dado en visibilizar la signifcativa concentración de estas estructuras en la mitad norte del área de estudio. Proponemos que tal concentración, inusual para el resto
del sur de Chile, podría estar relacionada con la intensifcación en la aplicación de esta técnica de
pesca durante tiempos históricos por parte de poblaciones hispano-indígenas, más allá de su uso
previo, de carácter precolombino.
A paucity of archaeological remains of Atlantic salmon in Northeast North America has been cited as evidence that the species may have been present in the region only during and after the Little Ice Age (ca. 1450–1850 AD), one of coldest periods of the Holocene. However, significant problems of preservation, recovery and identification remain. Here, improved methods of identification use vertebra structure to distinguish salmon from trout, and strontium/calcium ratios to differentiate sea-run from landlocked salmon. In addition to the Little Ice Age, Atlantic salmon is identified in tightly dated contexts at 7000–6500 and 3500–3000 calendar years BP, during climate periods that were comparatively warm and wet.
Rapid late Quaternary relative sea-level changes controlled shoreline position and stratigraphy of the inner continental shelf of the western Gulf of Maine. Seismic stratigraphic interpretation of approximately 1600 km of high-resolution seismic reflection profiles reveals distinctive shelf terraces, most abundant at a depth of 50-65 m. Characteristics of these features include: a discontinuous terrace form composed of unconsolidated sediment, a steep slope that dips seaward, a unique internal seismic stratigraphic sequence, and a surface texture of generally coarse-grained material. These shelf terraces are primarily erosional components of a lowstand shoreline, submerged by Holocene sea-level rise. Infrequently, littoral accumulation forms occur at the lowstand position. Similar accumulation forms are also found in shallower depths within sandy embayments. The inferred postglacial sea-level lowstand occurred at a depth of approximately 55-60 m below present and formed a shoreline during relative stillstand. These events occurred at 9500 ± 1000 BP, when the rate of isostatic rebound of the land equaled eustatic sea-level rise. -from Authors
Glacial marine sedimentation dominated the inner shelf and coastal lowlands of Maine between ca. 14,000 and 11,000 B.P. Three major seismic facies interpreted as glacial marine deposits beneath the inner shelf are identified by recent high-resolution seismic reflection profiling. These are: (1) GM-M, massive glacial marine sediment, a uniform, draping blanket with abundant ice-rafted detritus, either mud or diamicton; (2) GM-D, conformable glacial marine mud, with a distinct draping geometry, usually well stratified; and (3) GM-P, less well-stratified glacial marine mud with a distinctly ponded, variable geometry. These glacial marine facies are associated with underlying seismic facies interpreted as till, stratified drift and bedrock, and overlying seismic facies interpreted as Holocene littoral and marine facies. The glacial marine facies are contained within one of two seismic stratigraphic sequences, which record rapidly changing sea levels and sedimentary environments. Sequence G is composed of till, stratified drift, and glacial marine mud. It records the deglaciation of the northern Gulf of Maine and Maine coast. It is overlain by a distinct unconformity above the −60-m sea-level lowstand, which grades to a conformity in deeper basins, further overlain by seismic sequence H.
A critical issue concerning deglaciation of the area is identification of deglacial environments. A working hypothesis is that the initial deglaciation, ca. 18,000 to 14,000 B.P., was through a series of small, topographically buttressed, warm-based ice shelves, which were abundantly productive of poorly sorted sediment. These shelves may have formed and disintegrated in a sequential stepwise fashion, temporarily grounding on highs north of the major basins in the Gulf of Maine. After about 14,000 B.P., the ice front was a calving embayment, producing ice-rafted detritus, turbid suspensions, and subaqueous outwash. After 12,500 B.P., the ice margin was terrestrial, feeding melt-water streams and producing little ice-rafted detritus. The Maine inner shelf preserves this sequence in shelf valleys. Elsewhere, erosion during local relative sea-level changes has stripped bedrock highs of the majority of sediments, between the −60-m isobath and the inland marine limit (60- to 132-m elevation).
Incised-valley fills provide the greatest potential for preservation of sediments in a transgressive system. We compare examples from the coastal plain of Delaware and the glaciated bedrock terrain of Maine. Facies models developed in these areas suggest that 1/2 to 2/3 of the initial phases of transgression may be preserved below the shoreface ravinement surface in coastal-plain settings, recording initial fluvial, estuarine, lagoon, and some flood-tidal delta deposits. Coastal-plain systems are controlled by processes of open-ocean wave energy and back-barrier-tidal systems. Lithosomes are irregular and may be disconnected lenses. 10–30 m maximum thickness. 1–5 km normal to the shoreline, and 10’s of kilometers alongshore extent. Shoreface incision to a wave base of 10 m creates a ravinement unconformity. Incised-valley fills along the margins of a major estuary. Delaware Bay, record a similar sequence, but shoreface incision is smaller, approximately 1 m. In Maine, embayments are framed by bedrock, and cut into glaciomarine sediinents. The tide-dominated system accumulates sediment in the inner reaches but becomes progressively truncated by tidal-channel erosion at mid-embayment, creating an estuarine, tidal-ravinement surface. The outer, less geographically sheltered reaches arc dominated by wave erosion, which removes the majority of the sequence. Lithosomes are disjunct lenticular pods of a few meters to 10 m thickness and kilometer scale in lateral and longitudinal extent. In both cases, maximum preservation may occur as sea level reaches highstand, producing a prograding sequence that caps the earlier transgressive units.
Several glacial geologists working in Maritime Canada have developed a view of maximum late Wisconsin glaciation in which the Gulf of St. Lawrence and the Gulf of Maine were substantially ice-free, and ice calving into these embayments came from local ice domes, except for Laurentide ice calving into the Gulf of St. Lawrence along the Laurentide Scarp of Quebec. In contrast, most glacial geologists working in New England believe that Laurentide ice overrode all of New England and terminated as marine ice streams in the Gulf of St. Lawrence and the Gulf of Maine, and as terrestrial ice lobes in the Hudson River valley, the Connecticut River valley, and Great South Channel between Nantucket Shoals and Georges Bank. The view of New England glacial geologists is supported by numerous radiocarbon dates.
Glaciological models of ice dynamics along an ice-sheet margin consisting of local ice domes, ice streams, ice lobes, ice shelves, and calving bays have been applied to the Maritime Canada/New England region. These models show that the viewpoint of glacial geologists in Maritime Canada is compatible with conditions during deglaciation, but that the viewpoint of glacial geologists in New England is compatible with conditions during the late Wisconsin maximum. The undated ice margin north of the Gulf of Maine favored by Maritime Canadians cannot coexist with the dated ice margin south of the Gulf of Maine mapped by New Englanders. The ice divide between a Laurentide ice dome in Noveau Quebec or Hudson Bay and a local ice dome in the northern Appalachians must have had a saddle over the St. Lawrence River valley. A saddle is incompatible with the late Wisconsin glacial geology, but is consistent with the glacial features formed during retreat.
Deglaciation and postglacial crustal rebound near Portland, Maine, took place during a time of generally rising sea level. The relative positions of land and sea level at several points in time are indicated in part by: 1) glacial-fluvial deposits buried by marine silty clay to depths of 70 ft below present sea level, 2) radiocarbon-dated shells from emerged marine beds 160-250 ft above present sea level, 3) pollen-stratigraphic profiles of coastal sites underlain by marine sediment, which lack the late-glacial and early postglacial portion of the record, and 4) submerged tree stumps dating back to 4200 yr B.P. The position of a reference point in Maine with respect to changing sea level is graphically shown, using several alternative interpretations of late-Pleistocene eustatic rise of sea level as base lines. Only one of the constructions can be reasonably interpreted in terms of postglacial crustal rebound, demonstrating that areas of known crustal deformation can be useful in interpreting eustatic sea-level fluctuations.