de Fuca, another thrust southward down the Puget Trough. The ice sheet then retreated, but large alpine glaciers remained on the higher peaks.
The climate following the end of the ice age was mild for about three thousand years, and subtropical conditions extended as far north as Canada. During this warm period—which occurred about ten thousand years ago—the alpine glaciers retreated, postglacial erosion took place, and forests began to invade the country where the ice had prevailed.
The largest glaciers existing today in the Olympics—chiefly the ones on Mount Olympus and Mount Anderson—are believed by some geologists to be survivors of the ice age, but the smaller ones found throughout the Olympics are thought to have been formed during a subsequent cooling period—the so-called Little Ice Age of historic time, three thousand to five thousand years ago. Glaciers still exist on the higher peaks today, and the Olympics are noteworthy for having the lowest snow line in the United States (excluding Alaska). This line is the elevation above which snow can be found year-round. The largest glaciers in the range today vary from 1 to 3 miles in length. Although glacial carving is most pronounced on the northern and eastern sides of the mountains, all the larger valleys and canyons have been deepened and steepened by glacial erosion.
STREAMS AND LAKES
The rounded, dome-like configuration of the Olympic Mountains has resulted in a pattern of rivers that spiral outward from the central heights. These rivers, numbering perhaps a dozen having major significance, flow in all directions—west to the Pacific Ocean, east to Hood Canal (an arm of Puget Sound), north to the Strait of Juan de Fuca, and south into the Chehalis River drainage. Beginning in the north and proceeding clockwise around the mountain uplift, the major rivers are the Elwha, Dungeness, Quilcene, Dosewallips, Duckabush, Hamma Hamma, Skokomish, Wynoochee, Humptulips, Quinault, Queets, Hoh, Bogachiel, and Sol Duc.
The rivers are all short, but they rapidly carry enormous quantities of water to the sea because the precipitation on most of the peninsula is excessive. When the streams are in flood, they lose their normal clarity and roll along at high speed. At this time they are dangerous to cross, but they should always be treated with respect. Flooding occurs after heavy, sustained rains and when the snowmelt reaches its maximum in late spring and early summer. At this time the tributary creeks, unrestrained and brawling, as they flow through deep, narrow canyons, clatter like freight trains racing across the country.
The Olympic Mountains have many lakes, most of them located in the higher elevations. With the exception of five at low elevation—Ozette, Crescent, Quinault, Sutherland, and Cushman (which technically is a reservoir)—they are small and were created in various ways, including by glacial activity and dam building by humans. Most of the lakes are cold, but a few are warm enough to permit bathing. The lakes in the high country, at timberline or above, generally are thawed out and open by mid-July, but after winters of excessively heavy snowfall, if followed by a cool spring or summer, they sometimes remain frozen until mid-August. At this time many of the adjacent meadows—particularly on northern, shaded exposures—are still covered by a foot or two of winter’s snow while flowers bloom on southern slopes facing the sun.
VEGETATION ZONES
In mountainous regions, a phenomenon known as altitudinal zonation is present, caused by climatic changes that occur with an increase or decrease in elevation. As the elevation increases, the temperature decreases, and the climate becomes harsher, which has resulted in a classification called vegetation zones. Four such zones are present on the Olympic Peninsula—the Lowland Forest Zone, the Montane Forest Zone, the Subalpine Zone, and the Alpine Zone.
The Lowland Forest Zone ranges from sea level upward to elevations varying from 1500 to 2000 feet. This zone not only covers the lowlands surrounding the Olympics but also extends deep into the mountains by following the major rivers, gradually phasing into the Montane Forest Zone, which extends from the upper limits of the Lowland Forest Zone to an elevation about 3500 feet above sea level. The Subalpine Zone occupies the territory between the upper limits of the Montane Forest Zone and approximately the 5000-foot level. Above it, the Alpine Zone extends upward to the summits of the highest peaks.
Like everything in nature, the vegetation zones do not have distinct boundaries; instead, they blend into one another in an irregular manner. On cold northern slopes, for example, the Subalpine Zone at times extends well below 3500 feet. On the other hand, mountainsides with southern exposure often exhibit Montane Forest Zone conditions above 3500 feet. At times the Alpine Zone occurs at elevations below 5000 feet, particularly in the vicinity of glaciers.
On the peninsula, the Lowland Forest Zone has a mild marine climate, one typical of sea level at this latitude (45 degrees to 50 degrees north of the Equator). Within the mountains, this zone dominates the river bottoms and the lower foothills. The principal conifers are Douglas-fir, western hemlock, western red cedar, and Sitka spruce. Deciduous trees include red alder, bigleaf maple, black cottonwood, and Pacific dogwood. The luxuriant forest floor exhibits green mosses, flowering plants, and bushy shrubs. Included among the latter are willow, red elderberry, salmonberry, salal, huckleberry, devil’s club, and rhododendron. Low-growing plants include Oregon grape, skunk cabbage, fireweed, and many kinds of ferns. The luxuriance of this zone contrasts markedly with the dark, gloomy stands of the Montane Forest Zone on the slopes directly above. Elk herds live here the year around but particularly in the winter. Deer, bear, and cougar are also present. The bird life is varied—kingfishers and dippers on the streams, wrens and varied thrushes in the deep forests.
The Montane Forest Zone is largely confined to steep mountainsides, and the temperature is usually somewhat cooler than on the lowlands. This is a realm of dense, somber forests, mostly thick stands of tall conifers. The common trees are Pacific silver fir, western hemlock, and Douglas-fir, with a sprinkling of western white pine and western red cedar. Because the trees grow in heavy stands, and their crowns interlock, the sunlight that reaches the ground is soft and indirect, the air cool, fragrant, and moist. In fact, this canopy is so dense it intercepts the first winter snows, which often melt on warm succeeding days, never having reached the earth. On the steeper mountainsides, pistol-butted trees may be observed. Occasionally this results from ground creep, but the phenomenon is more often caused by heavy snow that bent the trees when they were young and pliable. Undergrowth in this zone is sparser than on the lowlands, but it encompasses a wide variety of shrubs and saprophytes. Vine maple, alder, and devil’s club border the streams; huckleberry, salal, and rhododendron clothe the drier slopes.
Rhododendrons bloom in late spring, bringing splashes of color to the forest along the Lower Big Quilcene Trail (Hike 80).
The conditions in this zone are less favorable to wildlife than in the other zones, thus animals are not abundant, but the chattering of chipmunks and Douglas squirrels may often be heard. Bird life is also less varied than in the other zones, but it does include the Canada jay, varied thrush, and several species of owls, including the spotted owl.
The climate is still cooler in the Subalpine Zone. This zone exhibits great variety—a mixture of subalpine trees, meadows, glacial lakes, swamps, and bogs. The forests in this zone’s lower levels blend gradually into the denser stands in the Montane Forest Zone below. In sharp contrast, in the upper levels open meadowland appears as the forest gives way to the treeless Alpine Zone.
The continuity of the Subalpine Zone forests is broken by the meadows. As in the Montane Forest Zone, the trees are chiefly conifers, but the dominant species are different—subalpine fir, mountain hemlock, and Alaska cedar. The trees are tenacious, having adapted themselves well to the harsh environment. Little groves are scattered over the grassy slopes and
