Summary: Oregon Prehistory
The NW Coast, Columbia Plateau, Inter-Mountain, Great Basin, and California chaparral eco-zones merge in present-day Oregon. The cultures, technologies, and economies of prehistoric Oregon reflect each one of these regions. The temperate climate and fertile environment allowed Oregon's prehistoric cultures to thrive for thousands of years.
Pleistocene Adaptation
The hallmark of the PaleoIndian period is that this is the within, but near the end of the Pleistocene Era--the Ice Age. The term "Paleo-Indian" refers to human adaptation to, and exploitation of, Pleistocene environments and associated plants and animals.
Very little data is available for this period of time. There are several reasons for this. First, there were very few people around this early. Populations grow over time. The initial occupation of North America was relatively late in comparison to the Old World, where the hominid species evolved. Second, time erases evidence through acts of nature. The older the archaeological site, the greater that chances that random events will destroy the site. In addition, all sites slowly decay. Their organic remains tend to be the first to go. Any features (soil stains, firepits, post molds, etc.) tend to erode away as artifacts and features are moved around by burrowing animals and plant roots. Artifacts and features in shallow soils are smeared out by freeze-thaw or moist-dry cycles. Third, the Willamette Valley is slowly filling up with sediments. Before the dams were built, the rate was about nine inches per thousand years. A site over 11,000 years ago would thus average about 8.25 feet below current surfaces. The chances of finding such sites are very remote. Continue with Pleistocene »
Holocene Adaptation
PHYSICAL ENVIRONMENT
This period marks the beginning of the Holocene where modern flora and fauna were used by prehistoric groups. The hunting of giant mega-fauna was no longer possible, as the giant animals had either died out or were hunted into extinction.
The temperatures rose, and the Pleistocene lakes began to shrink and wither away into alkali basins. The grasslands of the Great Basin were replaced by desert grasses, juniper and sage. The glaciers in the Cascades, Wallowa and Steens mountains rapidly disappeared. The flow of water from the Harney-Malheur Lake basin fell below the connection with the Malheur River, and became an internally drained basin.
Mt Mazama erupted about 6,800 year ago, throwing out roughly 11 cubic miles of pumice over vast areas of the NW. Ash has been identified as far north as Alberta, British Columbia and as far east as Montana. About 20 miles from the crater (now Crater Lake) the ash was one foot deep. The ash changed the landscape, and filled the rivers and streams for a long time. Ash may have impacted runs of anadromous fish such as the salmon, causing them to drop in numbers. The ash deposit is now used to date occupations of sites, as the date for this event is known, and the ash was deposited over such a large area of the NW. When artifacts are found under a primary deposit of Mazama ash, it is known the site is more than 6,800 years old.
BIOTIC ENVIRONMENT
The plants and animals were now modern in form. Hunters switched to deer, elk, antelope and small game such as rabbits and birds. Fishing also became important along the coastal streams and in the Columbia River system, with an increasing emphasis on the annual runs of the salmon. Coastal land forms continued to be buried under raising sea levels, so little is know about adaptations. The few sites that have survived demonstrate that shellfish were an important part of the diet as well as other river, estuary and near beach fish. Hunting of seals, sea lions and other pennipeds was also done.
Archaeologist roughly divide the climate history of this region into three periods: the Anithermal, the Altithermal, and the Medithermal. The first of these was a period of increasing warmth and dryness roughly similar to climates of today. Around 4,500 years ago, the temperature increased into the Altithermal, reaching a maximum warmth and dryness. This was followed by the Medithermal coming back to modern conditions. The Early Archaic roughly corresponds to the Anithermal.
The Archaic periods cover human activities during the Holocene after the end of the Pleistocene. The Holocene Archaic is divided up into three sub-periods: Early Archaic and Middle Archaic. These represent changing cultural adaptations to changing environmental conditions. Continue with Holocene »
Pyroculture Adaptation
The period of "pyroculture" began roughly 2000 years ago and extended to historical times. This period is marked by the presence of the bow and arrow. The climate was modern within fluctuations. There were droughts and periods of wet conditions, but these fell within modern patterns.
PHYSICAL ENVIRONMENT
The time period covered is roughly from 2000 years ago to contact with Euro-Americans. The climate was modern within fluctuations. There were droughts and periods of wetter conditions, but they fall within modern patterns.
BIOTIC ENVIRONMENT
Plants and animals distributions were essentially modern with small variations in relative density and abundance. Large scale manipulation of plants and animals through fire as a tool to reduce plants tied up in climax vegetation and to increase valued plant (and animals that depended on them) diversity and availability. The use of fire, what I call "pyroculture", started perhaps 3500-3000 years ago at the end of the Middle Archaic. Burning out climax vegetation, reduces the biomass tied up in cellulose (trees), and increases the diversity of the natural habitat. In the Willamette Valley, burning created an open grassland/oak mosaic between gallery riverine forests. The open grassland was the favored habitat for camas (a root "crop") and tarweed ( a seed "crop"). Oak expands with burning, so acorns (a nut "crop") also increased in relative abundance. Other plants used for food, medicine and fiber also increase in relative abundance with the use of fire. The oak/grassland mosaic was also favored habitat for deer and elk. The gallery forests along the streams were too wet to burn. The wood in these forests became the fuel source for camas processing ovens. Continue with Pyroculture »