The Olympic Mountains and Environs
D. B. Houston and E. G. Schreiner
The Olympic Mountains rise sharply from the surrounding coastal plain and foothills to dominate the 13,800-km2 Olympic Peninsula. The peninsula is bounded on the west by the Pacific Ocean, the north by the Strait of Juan de Fuca, and the east by the Hood Canal extension of Puget Sound (Fig. 1). The southern boundary of the Olympic Physiographic Province is arbitrary but is customarily drawn through the Chehalis River lowlands to Grays Harbor, a demarcation of earlier glacial outflow channels that drained the Puget lobe of the Cordilleran ice sheet. Adjacent lowlands to the east, including the Kitsap Peninsula, are usually considered part of the Puget Trough Province (Franklin and Dyrness 1988).
Mount Olympus is the highest peak at 2,430 m, and 37 other major peaks exceed 2,130 m. About 266 glaciers cover 46km2 of the range, with a total ice volume of 1.7 km3 (Spicer 1986). The largest glaciers, with 78% of the volume, are centered on the Mount Olympus massif. Eleven major rivers radiate from the mountains; Mount Anderson represents the hydrographic apex of the peninsula as water flows from it into the ocean, strait, and sound.
The complex geologic history of the Olympics has been described by Tabor (1987). The Crescent Formation, composed primarily of Eocene basalts, occurs in a horseshoe shape around the northern, eastern, and southern periphery of the range. The core rocks of the central and western part of the mountains are primarily marine sediments (sandstones, shales, conglomerates) of Eocene to mid-Miocene age (i.e., 20-58 million years old). Core rocks were partially thrust under the older peripheral rocks during subduction of the oceanic plate. Mountain goats occupy terrain composed of core rocks and peripheral rocks of the Crescent Formation.
The Olympic Mountains began uplift during the Miocene epoch (from 26 to 7 million years ago), and the mountain mass may still be rising (Tabor 1987). The radial drainage pattern was established early as water ran off in all directions from the rising domed landmass. The uplifted mountains intercept moisture-laden air from the Pacific Ocean and the high precipitation causes rapid erosion. Subsequent erosion has resulted in precipitous mountain slopes (Fig. 2). Moreover, the range was sculpted repeatedly by glaciers during the last 1.5-2.0 million
Studies of oxygen isotopes in fossils from marine sediments suggest that more than 20 ice ages occurred during the Pleistocene (Mix 1987), although the number that actually affected the Olympics is unknown. However, the most recent Wisconsin ice age is comparatively well-chronicled and involved several glaciations between about 100,000 and 10,000 B.P. At least six left records in the Puget Sound area, with the lastthe Fraser glaciationbeing the best documented. The following interpretation of glacial history was drawn primarily from Porter et al. (1983), Waitt and Thorson (1983), Ryder and Thomson (1986), Booth (1987), Tabor (1987), Henderson et al. (1989), and Pielou (1991).
The Fraser glaciation lasted about 10,000 years and consisted of 3 stades (periods of ice expansion) and 2 interstades (ice recession). The Fraser ice advance in the Olympics began with expansion of alpine glaciersthe Evans Creek stade. Although poorly dated on the Olympic Peninsula, at maximum advanceabout 21,000-18,000 B.P. (Porter et al. 1983; Waitt and Thorson 1983)glaciers extended down west-side valleys (Fig. 3). Glaciers in east-side drainages were smaller and were restricted to upper valley areas or headwalls (Long 1975). The Evans Creek advance coincided with the beginnings of an enormous ice buildup in the mountains of British Columbia.
Alpine glaciers retreated to undetermined positions up valleys following the Evans Creek stade (Booth 1987). This brief interstade was followed by advance of the Cordilleran ice sheet from British Columbia into the Puget Sound areathe Vashon stade (Fig. 3). The ice reached its maximum extent around 15,000 B.P., splitting into the Juan de Fuca and Puget ice lobes as it encountered the Olympic Mountains. Ice at the northeast corner of the Olympics was at least 1,050 m thick at maximum advance (Tabor 1987). The Vashon ice produced glacial lakes behind massive ice dams that formed in the northern and northeastern river valleys (to about 600 m in the Elwha). The ice sheet apparently did not contact the remaining alpine glaciers (Booth 1987; Tabor 1987). The spatial and temporal relations between ice sheets and alpine glaciers have important implications for the biogeography of endemic taxa; suitable habitat for alpine plants evidently persisted in or near the Olympic Mountains during both alpine and ice sheet advances of the Fraser glaciation.
The Vashon advance was short-lived; by 13,600 B.P., the two lobes had receded into a single lobe located in the northern Puget lowlands. A minor readvance (the Sumas stade) occurred about 11,500 B.P., but the extent and climatic significance of this stade has been questioned (Booth 1987). The Fraser glaciation ended about 10,000 B.P. when major climatic changes occurred.
The Wisconsin ice age gave way rapidly to a period of maximum postglacial warmth in the early Holocene. The timing of this climatic optimum varied across North America, but the period from 10,000 to 7,000 B.P. was apparently the warmest and driest part of the postglacial time in the Pacific Northwest (Barnosky 1984). The early Holocene warmth next yielded to the Neoglacial period of colder and wetter climates around 5,000-4,000 B.P. Alpine glaciers in western North America formed anew about 5,000 B.P. and subsequently retreated and advanced twice, at about 2,800 and 300 B.P. This last advance (actually a series of local advances and recessions) marks the Little Ice Age (LIA), which occurred from around A.D. 1350 to 1870. In the Olympics, the Blue and Hoh glaciers on Mount Olympus apparently reached their maximum LIA positions during the early decades of the nineteenth century (Heusser 1957; Spicer 1986). The glaciers retreated rapidly during the late nineteenth and early twentieth centuries. The retreat slowed in the 1950's, a minor advance occurred during 1960-80, and the ice fronts have been relatively stationary since. In addition to the recession of alpine glaciers in the late nineteenth century, Henderson et al. (1989) noted that large areas covered by year-round snow only 200 years ago are now open rock, scree, or talus. Abrupt transitions from unweathered rock debris to vegetated areas often mark the extent of the former LIA ice fields.
The climates of the Wisconsin ice age provide a convenient baseline against which to measure subsequent trends. Mean annual temperatures in the southern Puget Trough around 20,000-16,000 B.P. have been estimated to be 5-7 Celsius degrees colder than today; precipitation was perhaps 100 cm lessabout 50 cm annually (Whitlock 1992). The early Holocene temperatures of 9,000 B.P. were perhaps 1-3 Celsius degrees warmer than at present; precipitation was about half that of today, or around 75 cm. Temperatures during the LIA were perhaps 1-2 Celsius degrees colder than present (Lamb 1982).
Annual temperatures have increased nearly 1 Celsius degree in the Northern Hemisphere during the past century at the latitude of the Olympic Peninsula (Hansen and Lebedeff 1987). The increased temperatures are suggested by the records from Port Angeles, but the trend is not pronounced, probably because the station is under considerable maritime influence (Fig. 4). Port Angeles records show reduced annual and seasonal precipitation from about 1920 to 1940. Tree-growth studies confirm this, indicating that these 2 decades represent the most prolonged spring-summer drought in the past 300 years (Brubaker 1980). Shorter-term records show a trend of reduced snow in the Olympic Mountains; pronounced lows in 1 April snow measurements occurred in the 1960's and from the late 1970's to the present.
Climate differs across the peninsula. Mild maritime climates characteristic of the Pacific Coast give way to harsh cold in the alpine areas of the mountains, which in turn yields to dry, near-continental climate in the northeast (Fig. 5). The wettest location in the conterminous United Statesthe crest of the Olympic Mountain rangeis less than 60 km from the driest west coast site north of southern California. Eighty percent of the annual precipitation on the peninsula occurs from October to March; only 5% occurs in July and August (Phillips and Donaldson 1972; National Oceanic and Atmospheric Administration 1978). Winter precipitation falls mostly as rain below 300 m, as rain and snow between 300 and 750 m, and as snow at higher elevations. The lowest recorded minimum temperatures at low-elevation stations are around -16 to -19° C; the highest, from 34 to 40° C. Average January temperatures are near 0° C, with August maxima around 21° C.
The steep precipitation and elevation gradients of the mountains produce dissimilar microclimates in close proximity. For instance, a single ridge may be all that separates a permanent snowfield from hot dry habitats (Belsky and del Moral 1982). Moreover, dry alpine vegetation occurs within 15 km of oak savanna (now largely urbanized) and intertidal communities.
Pollen and macroscopic plant parts preserved in lake sediments and bogs have been used to infer the composition and distribution of plant communities that occurred in the Pacific Northwest since the Fraser Glaciation (summarized in Heusser 1977, 1978, 1983; Barnosky et al. 1987; Brubaker 1991; Whitlock 1992; Fig. 6). The species composition of plant communities was often so modified during glacial episodes that no modern counterparts exist (Whitlock 1992). The full glacial vegetation of 20,000-17,000 B.P. along the Pacific Coast contained elements of (but was not analogous to) the current subalpine parkland of the central Olympic Mountains. However, the composition of tundra-parkland in the Puget Trough, southeast of the Olympics, differed during this same period; there, the closest (albeit crude) modern analogue may be subalpine parkland of the northern Rocky Mountains. Forest composition has shown striking differences over time; the modern forests now characteristic of the Puget lowlands may not have been established until about 6,000 B.P. (Brubaker 1991; Whitlock 1992).
Most of the peninsula below 1,520 m is coniferous forest (Fig. 7). Elevational boundaries between vegetation zones (sensu Franklin and Dyrness 1988) are a function of the east-west precipitation gradient (Fig. 8). Low-elevation forests over much of the western Olympic Peninsula fall within the Sitka Spruce Zone and typically contain Sitka spruce (Picea sitchensis), western hemlock (Tsuga heterophylla), and western redcedar (Thuja plicata). The famous rain forests of west-side river valleys in the park (the temperate coniferous rain forest of Fonda 1974) are distinguished by massive Sitka spruce and western hemlock up to 90 m tall at densities of 60-270 trees/ha and by bigleaf maple (Acer macrophyllum) and red alder (Alnus rubra) laden with epiphytic mosses and ferns. The Western Hemlock Zone, often dominated by enormous Douglas-fir (Pseudotsuga menziesii) with western redcedar or western hemlock is the most common forest zone on the peninsula. The Western Hemlock Zone occurs on slopes above the Sitka Spruce Zone on the west side and is present at low and middle elevations elsewhere on the peninsula. The Pacific Silver Fir Zone typifies cool, relatively moist, middle-elevation forests of the western and southern portions of the peninsula. Silver fir (Abies amabilis) is characteristic, with a western hemlock component near lower elevation limits and mountain hemlock (Tsuga mertensiana) near upper elevation limits. The south-facing slopes at middle elevations in the dry north eastern Olympic Mountains support Douglas-fir and have been classified either as a separate Douglas-fir Zone or as part of the Western Hemlock Zone (Henderson et al. 1989). Here, Douglas-fir-dominated forests grade into subalpine fir (Abies lasiocarpa) forests (i.e., the Silver Fir Zone is absent from these dry slopes).
Forests and tree clumps in the Subalpine Fir Zone of the dry northeastern Olympic Mountains are dominated by subalpine fir with components of lodgepole (Pinus contorta) or whitebark pine (Pinus albicaulis; Henderson et al. 1989). Meadows occur generally above 1,520 m in the zone and are dominated by grasses, forbs, sedges, spreading phlox (Phlox diffusa), or a few ericaceous shrub species. High elevation forests and tree clumps elsewhere in the Olympic Mountains generally include mountain hemlock, subalpine fir, and sometimes silver fir. These represent the Mountain Hemlock Zone. Ericaceous shrubs, forbs, and sedges dominate meadows in this zone.
Subalpine and Alpine Meadows
We identified 16 meadow communities in subalpine and alpine areas above 1,520 m (Fig. 9 and Appendix A1). Two communities with low total plant cover occurred at environmental extremesone on highly disturbed, dry sites (Astragalusscree); the other on raw substrates where snowmelt was late (Luetkea pectinataSaxifraga tolmei community). Communities between these extremes seemed to be arrayed along a broad snowmelt and moisture gradient similar to that described by Kuramoto and Bliss (1970). Six community types on drier sites contained spreading phlox as a dominant or codominant species. Wetter sites were dominated by showy sedge (Carex spectabilis), pink mountain heather (Phyllodoce empetriformis), Merten's mountain heather (Cassiope mertensiana), or blueberry (Vaccinium deliciosum). Community composition was influenced by the relative stability of substrate, rock size, and glacial history. Our study extended the subalpine meadow work of Kuramoto and Bliss (1970) to steeper slopes and to the less meadowlike vegetation of rocky outcrops and talus slopes, and covered a larger geographical area than the regionally limited studies of Belsky and del Moral (1982), Pfitsch and Bliss (1985), and Smith and Henderson (1986).
Many environmental factors influence community composition in the subalpine and alpine zones. Earlier studies have shown that plant composition depends on snow retention (Bliss 1969; Canaday and Fonda 1974), temperature (Kuramoto and Bliss 1970), soil moisture (Kuramoto and Bliss 1970; Belsky and del Moral 1982; Pfitsch and Bliss 1985), magnitude of soil disturbance (Bell and Bliss 1973; Belsky and del Moral 1982; Pfitsch and Bliss 1985), microenvironment (Peterson 1971; Loneragan and del Moral 1984), and competitive interactions among species (del Moral 1983a, 1985). Soil moisture and disturbance are most often cited as influencing vegetation patterns. Mountain goats are most conspicuous in subalpine and alpine areas, but they occupy all vegetation zones (except Sitka spruce) at some season or place on the peninsula.
The abundant precipitation and acidic soils of the peninsula do not favor preservation of archeological materialsrecords of early human occupation are sparse and are likely to remain so (Wessen 1990). Scattered Clovis-type projectile points found around Puget Sound suggest that Paleo-Indians may have occupied the area by 11,000 B.P., but none of the points has been associated with dated archaeological deposits (Schalk 1988).
Human occupancy of the Pacific Northwest from 10,000 to 3,000 B.P. (the Old Cordilleran period) is somewhat better documented. On the peninsula, the oldest dated archaeological site from this time is a 5,000-year-old hearth located at 1,500 m in the northwest Olympic Mountains (Bergland and Marr 1988). People colonizing the area seem to have been derived from two distinct ethnic pools: groups that moved down the Columbia River from interior North America around 10,000 B.P. and bands that dispersed south down the coast about 9,000 B.P. (Bordon 1979; Carlson 1990).
More recent shell middens occur commonly in coastal areas and date from about 3,000 B.P. The middens and associated vertebrate remains suggest that semisedentary land use systems that evolved during the past 3 millennia were based on the exploitation of marine resources such as shellfish, fish, and marine mammals (Croes and Hackenberger 1988; Schalk 1988; Wessen 1990).
European contact with the Amerindian cultures of the peninsula occurred during the 1770's, if not earlier (Evans 1983; Capoeman 1990). As elsewhere in North America, aboriginal cultures were decimated by diseases of Europeans. By 1885, the Quinault population had declined to about 100 from the 1,000 of a century earlier (Capoeman 1990).
European settlement of the peninsula began in the 1850's; and by 1890 isolated settlements and homesteads were present throughout the low coastal areas (Evans 1983). The Olympic Mountains themselves evidently remained largely unexplored until the 1880's to 1890's (Appendix B).
Olympic National Park encompasses about 3,700 km2 as two separate unitsa central mountainous core of 3,530 km2 and a narrow strip of 170 km2 that extends for 84 km along the Pacific coast (Fig. 10). About 96% of the park is designated wilderness. Considerably less than 1% is developed with roads, trails, campgrounds, and structures that are located mainly around the periphery.
Lands surrounding the park are managed primarily for wood products by the Washington Department of Natural Resources (1,600 km2), the U.S.D.A. Forest Service (Olympic National Forest2,800 km2), and private timber companies. Five Indian reservations also border the park. About 350 km2 of the Olympic National Forest are also designated as wilderness. These wilderness parcels occur as six units abutting the eastern and southern boundaries of the park. Mountain goats are established only in the mountainous unit of the park and the adjacent Olympic National Forest, particularly in the wilderness blocks of the forest.
The epic struggle to establish the park pitted conservationists against politically powerful timber interests; Evans (1983) and Lien (1991) documented the stormy legislative history of the park. The core of the Olympic Mountains was included in a national monument created in 1909, but wrangling over the fate of potentially merchantable timber at lower elevations of the monument resulted in several subsequent boundary changes. The park has been administered since its establishment in 1938 by the National Park Service, an agency authorized in 1916 (within the U.S. Department of the Interior), which developed policies for the management of the park (National Park Service 1988).
Last Updated: 12-Dec-2007