Man-made fibres are to be distinguished from natural fibres such as silk, cotton, and wool. Natural fibres also consist of polymers (in this case, biologically produced compounds such as cellulose and protein), but they emerge from the textile manufacturing process in a relatively unaltered state. Some man-made fibres, too, are derived from naturally occurring polymers.
Mount Si is located in North Bend, Washington (USA). The climb is 4,167 feet (1,270 meters) and 4 miles from the parking lot to the summit plateau. Vertical elevation change is about 3700 feet and starts at about 700 feet. The route meanders through several different ecosystems as temperatures and average rainfall vary with elevation.
Surveyor's mark embedded in the observation tower notes the elevation of 6684 feet above sea level. The peak is the highest mountain in the United States east of the Mississippi River, and the highest in all of eastern North America south of the Arctic Cordillera. The nearest higher peaks are in the Black Hills of South Dakota and the highland foothills of Colorado.