The Siskiyou Crest is a striking geologic feature straddling the Oregon/California border, that divides the great river basins of the Klamath and the Rogue. It stretches through the heart of the world-class Klamath-Siskiyou bioregion, extending some 90 miles from the Cascade mountains toward the coast. It is home to one of the highest concentrations of botanical diversity on the continent and forms one of the most valuable wildlife corridors in the West.

The Siskiyou Crest inhabits an auspicious junction of space and time. It is exceedingly unusual among mountain ranges, with ridges that run west to east, whereas almost all other mountain systems in North America stretch north to south. This west-east orientation gives the Crest the qualities of a “Land Bridge,” and offers the highest quality habitat corridor connecting wildlife between the Coast Ranges of California and Oregon and the massive cordilleras of the Cascade and Sierra ranges.

The Crest is a crossroads of the highest order, containing overlapping elements from distant ecosystems in all four directions. It lies on the northern edge of ranges for species that comprise the legendary California floristic province, and the southern reach for many trees and animals that form the great forests of the Pacific Northwest. It is the eastern extent of home ranges for countless coastal life forms, and the western tip of habitat for desert dwellers reaching over from the Great Basin to the east.

On top of this intersection of great geographic provinces, the rugged wildlands surrounding the Siskiyou Crest are also a melting pot where organisms from the deep past mix with the flora and fauna of the future. The Crest fascinates scientists for being both a refugia for ancient species once widespread, and a birthing ground for new species just evolving into being. Both of these attributes stem from the mixture of a stable, mild climate that has persisted for millennia. This has allowed evolutionary processes to unfold uninterrupted by glaciation or volcanism while species from afar retreated here as other landscapes became inhospitable to them.

The region around the Crest is also host to a tremendous diversity of microclimates formed by extremely complex geology and steep, twisted topography. One of the unusual rock types present, serpentine, is actually toxic and contains heavy metals like chromium and nickel that bleed into the soil. Strangely, this toxicity contributes greatly to the diversity of the rare plants found here, as many species have evolved to tolerate this soil type and can grow freely where more common competitors are excluded.

Diversity of form piled on top of diversity of type is a hallmark of the Siskiyou Crest, and a strikingly high percentage of plants and even animals found here are found nowhere else on earth. The Siskiyou Mountain salamander (Plethodon stormi), the Applegate gooseberry (Ribes marshallii) and the Yreka Phlox (Phlox hirsute) are just a small sampling of the endemic specialties found deep in the folds of these mysterious canyons.

“In 1975, Wayne Roderick of the University of California Botanic Garden, Berkeley, asserted in the Journal Four Seasons that Cook and Green Pass (at the center of the proposed monument) has ‘the largest single aggregation of native plant species known to occur in one limited area in California.’” -Page F-7, Rogue River National Forest FEIS, Land and Resource Management Plan

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