prehistory and paleoenvironments of the silvies plateau, harney basin ...

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knowing the setting. both present and past, within which archaeological sites are found that we can understand their function. 8y combining the archaeological ...
Project Report Number 8

PREHISTORY AND PALEOENVIRONMENTS OF THE SILVIES PLATEAU, HARNEY BASIN, SOUTHEASTERN OREGON

by

Kenneth C. Reid, John A. Draper, and Peter f . W~and

Center for Northwest Anthropology WashinQ'lo n State University

Pullman 1989

Chapter 4 VEGETATION, VEGETATION HISTORY, AND STRATIGRAPHY by

Peter E. Wi gand

Introduction To understand the human prehistory of the forests of south-central Oregon , the story of the forests themselves must be known. It is only by

knowing the setting. both present and past, within which archaeol ogi cal sites are fo und that we can understand their function . 8y combining the arc haeological data which has been recovered from these sites with the regi onal paleoenvironmental reconstruction we can arrive at a clearer understanding of how these places may have been used and how they fit into

the yearly pattern of Nat ive Ameri ca n Tifeways. It is too simplistic to ass ume that the ponderosa pine forests that we find today in the mountains

north of Burns, Oregon have been there forever, or for that matter, even for the 10 ,000 to 11,000 years since the last glacial.

forest is not a constant , unchanging environment. man, and by changing climate.

We know that today the

It is affected by fire, by

To reconstruct ·the f ong term history of these forests, we must look for

nearby places where both foss il pol len and plant macrofos sil records may have preserved a record of these changes . Once the past environmental backdrop has been reconstructed, we can look beyond the reality of the present env i ronment with its obscuri ng bias to assess the archaeo 1og1 ca 1 record. Thus we can better understand the lifeway of peoples that once roamed the hills around the Silvies Ri ver Valley.

In order to reconstruct the paleoenvironmental state, the modern natural setting was examined for clues of past environments. Evidence for the vegetation history of the area was sought in lake, · spring and meadow deposits, and in fossil woodrat nests where pollen and plant macrofossils may have been preserved . · The stratigraphy of exposed sediments was examined for changes in depositional . processes or weathering to provide additional information on past environments. to this end, wet meadows and springs were tested for the presence of preserved pollen and plant macrofossils . Once these localities were i dentified they were sampled and analyzed. Suitable rock exposures were then searched for ancient woodrat middens with radiocarbon datable plant macrofossils and pollen that would provide time capsules of local vegetation. Once fo und , these middens were then collected, sampled, analyzed, and dated. Finally, arc haeological sites, geological trenches, and natural exposures were ex amined for widespread correlatable (and/or datable) changes in strati graphy that would provide evidence of s.:ignificant events in sediment deposit ion or soil formation that might be related to vegetation or climate history.

38 The direct importance of knowing the vegetation history of the region can be seen in the reasons given by the Northern Paiute for coming to the

Silv ies Valley . Ethnographic investigations with the Burns band of the Northern Paiute indicate that historically they came up the Si1vies River to the hills north of Burns to collect berries and hunt deer and elk in the fall (Couture 1978). Many other plants were available, however, and may also have been used . Therefore, modern vegetation around the archaeological sites was described and the availability of plants that could have been used by native peoples for food or raw materials were noted. Modern Vegetation To provide a modern ana l ogue for paleoecological studies the modern vegetation was characterized . Because Hall Creek and the slopes around it

(Figure

4-1)

support

abundant

and

varied

co llection and identification began there.

plant

communities,

initial

Over the two field seasons. 77

plants were collected and identified. An additional 12 species were collected at Craddock Meadow and three more were collected and added to the list from Owen Spring. Other important plant species (e.g., golden currant. camas) that would have been accessible to native Americans 1 iving in this area are noted in the text. When possible, both seeds and pollen were

co 11 ected from these plants for compari son wi th foss i 1 pollen and plant m.a crofossils that might be recovered. Five other plants were identified to species level in the field but not collected. Some species were in too poor a condition to identify beyond genus level. Scientific nomenclature follows

Hi tchcock and Cronqui st (1973). Various ethnobotanical sources were examined for mention of the use of

spec ific plant species .

Species definitely used by Nati ve Americans in the

northern Great Basin and adjacent areas have been noted · in the plant lists.

Vanovsky (1936) is a secondary reference that cites many other primary sources for native plant use . Because plant nomenclature often has changed during the past 40 y ears, occasionally it is the old species name that appears in the sources cited.

Plant associations in the hills west of the Silvies Valley vary partly by e1evation--500 meters separates the 1387-meter (4,550 ft.) floor Qf Sil vies Valley from the 1887-meter .(6,189 ft.) top of Gold Hill near Hall Creek . However, differences in slope, aspect, soil depth and distance to water sources result in strikingly diverse plant associations over very short

distances (Table 4-1 ). Despite ·historic Euroamerican disturbance, willows and golden currents

(R ibes auerum) still line the Si1vies River. In June patches of blue-spiked Early Camas (Camassia guamash) color the fields of sedges and grasses that blanket the valley floor . Before ditching and draining of the valley floor, camas fi e 1ds must have been much more extens i ve.

Below 1,420 meters (4 ,658

ft.) the hills west of the Si1vies are characterized by sagebrush steppe. Above t hi s in valley bottoms and on slopes with deep soil a mixed conifer forest of ponderosa pine and Douglas fir predominates. On north-facing sl opes and areas affected by col d air drainage, ponderosa pine gives way to grand fir . Estimating from cut trees, most ponderosa pines are between 180 and 250 years old. Dougla"! firs a·re between 50 and 150 years old, and grand