Only about 11,000 years have passed since the last wave of northern ice retreated and laid bare Olympic rocks. Since then the moist and gentle climate has favored the growth of plants and the development of soil. The present Olympic forests and flowering meadows are products of a succession of plantlife from the first lichens and mosses that grew on Olympic rocks. Animals returned when the ice retreated. Plant eaters and meat eaters, large and small, throve in abundance. When primitive man came, he found the land and sea kindly. He easily obtained what he needed for food, clothing, and shelter without depleting the supply.
While most of the Northwest was being explored and settled by the white man during the 19th century, the bulk of the Olympic Peninsula remained virtually unknown. Its rugged mountains, dense forests, and isolation contributed to the delayed advance of modern civilization to this northwesternmost corner of conterminous United States. The Olympic Peninsula thus remained one of the last frontiers, and the park retains genuine wilderness quality, even to its boundaries which descend to sea level.
In this piece of original America the perceptive eye and mind will find a functioning model of nature—a model of earth forces, climate, and life.
The Mountains Are Formed
The present Olympic Mountains were born between 12 and 20 million years ago when western Washington was pushed up into a great range that extended from Cape Flattery southeastward to the eastern part of the State. At the same time, the land to the north and south was depressed and remains depressed today as Juan de Fuca Strait and Chehalis Valley, respectively. The Olympics were further elevated about 5 million years ago. This coincided with the building of the Cascade Mountains and the down-folding of the land between to form the Puget Sound trough. The Olympics were now isolated, having lowland on all sides.
Olympic rocks formed in shallow seas that at least five times have covered western Washington. Sediments washed from adjacent land areas and accumulated on the sea bottom. Muds became shales and sands were cemented into sandstones. Molten lava erupted through these beds and was quickly cooled by the water. Thousands of feet of rock material formed in this way.
When earth forces lifted the sea floor, the sea disappeared, and for long periods there were mountains where the sea had been.
Pressure and heat changed the rocks, especially the sedimentary rocks, which became harder and tougher. Shale changed progressively into slate and phyllite. All of these rocks are found in the Olympic Mountains. The sedimentary rocks and lava flows, originally horizontal on the sea floor, were tilted and folded when uplifted and this is how we see them today.
Long periods of erosion have removed thousands of feet of rock and remolded the Olympics into magnificently rugged mountains. Thus, earth forces build mountains and water slowly carries them back to the sea. So it has been since the first rains fell upon the cooling earth.