Pacific NW tidal wave in 9230 BP
Stuart Harris, Palo Alto CA. Stuhar@verio.com April 2000.
Summary
In 9230 ±60 BP [8,350 BC], a great tidal wave inundated the Pacific NW coast, obliterating the coastal population. Shortly afterward, beginning 9195 ±35 BP, many coastal sites were repopulated with Yurok / Algonquin-speaking people, who had just arrived after an arduous journey from Europe across Asia, the Bering Strait and Alaska. (Supporting evidence for interior BC, the Queen Charlottes and Coastal BC sited.)
Introduction to NW Tidal Waves
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Because of enormous sediment outwash from melting of the last glaciers,
tidal waves periodically flood the Pacific Northwest coast. These tidal waves
result from submarine landslides, called turbidites, which are triggered by
earthquakes. Turbidites occur when a massive wedge of sediment along the edge
of a continental shelf abruptly slides into a deep trench. Figure 1 shows the Juan de Fuca plate off the coast of
Washington and Vancouver Island. This plate pushes against and dives beneath
the North America Plate, thus creating a deep subduction zone. The Columbia
River and Juan de Fuca channel provide the sediment. Figure 1. Juan de Fuca Plate sliding under the North America Plate. |
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Heal Lake records tidal waves
Heal Lake, a small pond on Vancouver Island near Victoria, elevation 126m (416 feet), has faithfully recorded the largest tidal waves and many smaller ones. Major tidal waves create a sharp change in sediment. All waves knock down trees growing around the perimeter. After Heal Lake was recently drained, cores were taken from over 700 pristine logs at the bottom of the lake by Qi-bin Zhang of U. of Victoria. Unexpectedly, the logs clustered around certain dates going back to 9000 BP. Instead of a continuous sequence, the logs measured tidal waves. Figure 2 illustrates these tidal waves along with a rough estimate of their height. In addition to Heal Lake are shown three other dated sources for comparison: drowned villages, drowned forests along the Oregon coast, and interbedded sand layers from Willapa Bay in Washington. The last major tidal wave occurred in 1110 BP; no logs recorded the most recent tidal wave of 1700 AD.
Figure 2. Record of tidal waves at Vancouver Island.
This paper examines the tidal wave of 9230 BP that decimated the coastal population.
Sudden warming in 11,700 BP
The bottom of the Heal Lake dates to 12,100 BP, as shown in Figure 2. This may have been when glaciers retreated from Vancouver Island, or may have been the first tidal wave. As shown in Figure 3, the record of CO2 in ice cores at Vostok, the earth had been warming slowly but steadily since 18,000 BP. Suddenly around 11,400 BP, the temperature rose very rapidly, hitting a peak in 11,013 BP, then declined. This abrupt transition from hot to cold marks the start of the Younger Dryas. Rapid heating plus drenching rain caused intense melting of glaciers, which raised sea level and left huge unstable sediment deposits at the mouths of rivers draining North America.
As glaciers melted and temperatures rose, the Pacific Coast became habitable. However, no record has been found at any sites in British Columbia prior to a tidal wave in 10,900 BP.
Tidal wave in 10,900 BP
Heal Lake preserved a record of a major tidal wave in 10,900 ±25 BP. Figure 3, a core from Heal Lake, shows three unconformities. The bottom unconformity is either a tidal wave or the end of glaciation at 12,120 BP. The middle unconformity is the tidal wave at 10,900 BP. "The material used to date the beginning of the climatic event [was] forty lodgepole pine cones lying directly on the top of the gyttja beneath colluvial deposits at the lake's southern margin. d13C values in the sand and gravel colluvium from the southern lake margin are enriched compared to the gyttja below. Whether this enrichment is related to the Holocene transition and therefore would imply an interval with either a very low deposition rate or lake level decrease, or is due to increased terrestrial carbon input, has not yet been determined." The upper unconformity between the colluvium and gyttja marks the tidal wave at 9230 BP.
Figure 3. Heal Lake stratigraphy, showing a major event at 10,900 BP.
Source: Holocene 13C, Climate and Carbon Cycling, University of Washington, Western Regional Center Director's Report, Thomas H. Suchanek, Director; Minze Stuiver; Paula J. Reimer.
Gyttja: A Swedish word pronounced "yuetya." A nutrient rich sedimentary peat consisting mainly of plankton, other plant and animal residues, and mud. It is deposited in water in a finely divided condition.
· Example: At c. 6,500 BP the deposition of gyttja (representative of deep, open water) was replaced by the in situ deposition of wood peat.
· Example: Unit 1 often grades into, or is sharply overlain, by brown or black gyttja, a mixture of inorganic sediment and organic (algal) components (Unit 2). Unit 3 is either a silty gyttja or a mineral sediment which marks the onset of the Younger Dryas (Mott, 1975).
Occupation began at Charlie Lake Cave
The earliest British Columbia habitation record is an inland rock shelter called Charlie Lake Cave. Occupation began 50 years after the tidal wave of 10,900 BP. This cave served as a summer campsite for hunting bison and deer. A thousand years later, marine sites at Arrow Creek, Namu and Richardson Island were occupied, possibly by different people who specialized in gathering fish and shellfish.
British Columbia archaeological sites
Figure 4 shows all radiocarbon dates for British Columbia occupation sites from 11,000 BP to 8,500 BP. There are five sites: Charlie Lake Cave terminates at the wave, three continue after the wave, and one starts after the wave. Dates for shell, barnacle and sea otter have been adjusted for the marine reservoir effect. If there were other occupied sites, they do not appear in the Canadian Radiocarbon Database.
Figure 4. Earliest BC occupation sites, showing the effect of the tidal wave.
Occupation continued at all sites until terminated by a tidal wave in 9230 ±60 BP. The uppermost occupation layer from 9500 to 9200 BP is missing, swept away by the wave. Several wood and charcoal dates between 9300 and 9400 BP originate as driftwood piled up as a result of the wave. The tidal wave date was obtained from logs in Heal Lake.
Arrival of Yurok / Algonquins
Shortly after this tidal wave, a large group of Yurok/Algonquin speaking people arrived. They had just completed a long and arduous migration from central Europe, across Asia, paddled across the Bering Strait, then traveled down the coast from Alaska. Yurok history recounts that their migration down the West Coast was very difficult and food was scarce. As they traveled south, small groups broke off and settled along the depopulated region. The most accurate date for the earliest occupation comes from barnacle at Arrow Creek and shell from Echo Bay, 9195 ±35 BP.
Yurok historian Lucy Thompson provides a confirming date. In 1916 she wrote that when her ancestors arrived at the Klamath River, Redding Rock was on dry land attached to the mainland. The low mound at the base of this needle-like rock is 50 ±2 meters beneath the sea. The last time this mound was part of the mainland was 9200 +/-200 BP [8,350 BC].
Her history mentions no other tribes until the Klamath River, a curious omission.
“The Talth [spiritual leaders who took the place of chiefs] would stop after days of fatigue and hunger, and build another lodge where their members would worship at the sacred shrine. … The Talth would plant the herb, walth-pay, at their stopping places during their travels, and it would readily take root and grow. At almost every stopping place, some of our people were left, and God would give them a language. They would inhabit the locality permanently and branch out to other localities, while our part of the people traveled on until they reached their final earthly home on the Klamath River, which we call Health-kick-wer-roy. And here we found the white race (Wa-gas)." Source: Lucy Thompson, "To the American Indian,"1916, p78. Lucy was a Talth.
Notes on BC sites
Charlie Lake Cave is on the north side of Stoddart Creek, northwest of Fort St. John, Peace River drainage, British Columbia. Charlie Lake Cave is one of only a few known archaeological sites in northern North America that date to before 10,500 years ago, and one of even fewer with a well preserved stratigraphic record of human activities. "Three seasons of fieldwork at this site have revealed a sequence of stratified deposits that spans the Late Pleistocene and entire Holocene. Analysis of sediments, radiocarbon dates, faunal remains, and artifacts show that the site was first occupied by people at about 10,500 BP, when local environments were more open than today. By 9500 BP, boreal forest had moved into the area, and human use of the site was minimal until about 7000 BP, when a brief occupation of the site probably included a human burial. Use of the site intensified after about 4500 BP, possibly because the cave became more accessible. The site was used both as a residential base camp and as a more temporary hunting station or lookout." Sources: Driver, 1988, 1996; Driver and Hobson, 1992; Driver, et al. 1996; Fladmark, 1996; Fladmark, et al. 1988.
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Figure 5. Charlie Lake Cave location.
(source: Paleoecological and Archaeological Implications of the Charlie Lake
Cave |
Namu is just north of the mouth of Namu River, British Columbia. This site is a deep, stratified shell midden deposit. "Period 1, 11,000 to 7000 BP, lacks both bone artifacts and faunal remains due to soil acidity in the absence of mollusk shell. Artifacts from this period consist of lithic workshop debris from cobble reduction, along with finished and unfinished tools; microblade technology appears in the middle of the period." Source: Cannon (1991)
Richardson Island is southeast of Moresby Island, Queen Charlotte Islands, British Columbia. This is a stratified site on a raised beach 14-18 m asl [above sea level]. "Augering and test excavations have revealed more than 40 artifact-bearing strata. An early component is referred to the Kinggi complex, dating 9300 to 8900 BP, with technological similarities to pre-9000 BP assemblages extending from Alaska to California. Around 8900 BP, tabular to conical microcores are added to this complex, representing the early Moresby tradition that continues until 8000 BP." Sources: Fedje and Christensen, 1999.
Arrow Creek site is on the north bank of Arrow Creek near the mouth of Matheson Inlet, Moresby Island, Queen Charlotte Islands, British Columbia. This site is situated at the modern tidal limit. "The artifact distribution and context suggest discard into the intertidal zone or secondary deposition into subtidal sediments." Sources: Fedje and Christensen, 1999; Fedje, et al. 1996a, 1996b; Josenhans, et al. 1995.
Echo Bay is southeast of Moresby Island, Queen Charlotte Islands, British Columbia. This site spans the intertidal to uppermost subtidal zone of a small bay near the mouth of Echo Harbor. "Except for a small area with a buried artifact-rich layer, the sediments have been heavily disturbed by burrowing mollusks and wave action. Apparently the three available dates somehow limit the age of the artifacts, but the field relationships are not yet clearly reported." Sources: Fedje and Christensen, 1999.