Olympic National Park – Geology
The mountains themselves are products of accretionary wedge uplifting related to the Juan De Fuca Plate subduction zone. The geologic composition is a curious mélange of basaltic and oceanic sedimentary rock. Unlike the Cascades, the Olympic Mountains are not volcanic, and contain no granite.
Olympic National Park – Alpine areas, sub-alpine forest and wildflower meadow
Within the center of Olympic National Park rise the Olympic Mountains whose sides and ridgelines are topped with massive, ancient glaciers.
The western half of the range is dominated by the peak of Mount Olympus, which rises to 7,965 feet (2,428 m). Mount Olympus receives a large amount of snow, and consequently has the greatest glaciation of any non-volcanic peak in the contiguous United States outside of the North Cascades. It has several glaciers, the largest of which is the Hoh Glacier, nearly five kilometers in length. Looking to the east, the range becomes much drier due to the rain shadow of the western mountains. Here, there are numerous high peaks and craggy ridges. The tallest summit of this area is Mount Deception, at 7,788 feet (2,374 m).
Olympic National Park – Coastline
The beach has unbroken stretches of wilderness ranging from 10 to 20 miles (16 to 32 km). While some beaches are primarily sand, others are covered with heavy rock and very large boulders. Bushy overgrowth, slippery footing, tides and misty rain forest weather all hinder foot travel. (Times to hike should typically be doubled.) The coastal strip is more readily accessible than the interior of the Olympics; due to the difficult terrain, very few backpackers venture beyond casual day-hiking distances.
Olympic National Park – Temperate rain forest
The western side of the park is mantled by temperate rainforests, including the Hoh Rainforest and Quinault Rainforest, which receive annual precipitation of about 150 inches (380 cm), making this perhaps the wettest area in the continental United States (the island of Kauai in the state of Hawaii gets more rain).
As opposed to tropical rainforests and most other temperate rainforest regions, the rainforests of the Pacific Northwest are dominated by coniferous trees, including Sitka Spruce, Western Hemlock, Coast Douglas-fir and Western redcedar. Mosses coat the bark of these trees and even drip down from their branches in green, moist tendrils.