The Western Cascades of Oregon are not just the western side of the Cascades. The Western Cascades are a very old mountain range and are sometimes called the Old Cascades. They began around 40 million years ago as a result of volcanic activity which continued until at least 10 million years ago. Since then, they have eroded into a series of ridges cut by river valleys. Much more recently, the volcanic activity moved a little farther east. This is when the great volcanos of the High Cascades formed. Mount Hood, the highest peak in Oregon, is less than a million years old. The High Cascade eruptions were so close that they buried some parts of the older Western Cascades, making it hard to distinguish these two separate ranges in places. A look at satellite photos shows the difference more clearly than can be seen on the ground. The Western Cascades run more or less along a north-south axis from central Washington into northern California but mostly lie in Oregon. Several Western Cascades peaks in the south, such as Hershberger Mountain and Rattlesnake Mountain, reach over 6000′, but most are in the 4500-5500′ range, well below treeline. The southern end of the range appears to be younger, and along with decreased erosion from the drier climate, this may account for the increased elevations farther south.
While the prominent peaks of the High Cascades attract throngs of people to their spectacular scenery, the lower and more sedate Western Cascades are far quieter. On many Western Cascades trails, it is uncommon to see any other hikers, especially during the week. While their old weathered ridges may not seem to be as exciting to hikers, to wildflower lovers, they are actually more interesting and diverse. Their greater age has allowed far more plants to become established. A typical hike in the Western Cascades will yield 3 or 4 times as many species as one of the same distance in the High Cascades.
The high rainfall and relatively milder temperatures of the Western Cascades have helped to cover the mountains with vast forests mainly consisting of Douglas-fir, true firs, and hemlocks. These are some of the most productive forests in the world. As a result, there has been a great deal of logging in these mountains. A view from any peak reveals a patchwork of different shades of green as a result of the different ages of forests. One silver lining from a hiker’s point of view is that there is easy access to many good botanizing sites. While much of the old growth forest is gone, many of the best botanizing trails begin in stately forests still filled with giant trees. Beneath Western Cascade forests is an incredibly rich undergrowth of shrubs and herbaceous plants. The lodgepole pine forests of the High Cascades are quite depauperate in comparison. Exposed rocky areas are less common than in the High Cascades, but hold many wonderful plants. Many of the accessible rocky sites are old fire lookouts and have fabulous views. Open meadow habitat becomes more frequent at the drier southern end, while bogs and other wetlands are more prevalent to the north. Even roadcuts are home to many exciting plants. The diversity seems endless. I encourage everyone to head out to some of these wonderful trails and botanizing areas, and I hope the information presented here will help enrich your experience.