16. Phantom Ship--A rugged island rising dramatically 175 feet above the lake surface, the "ship" is a remnant of an ancient volcano predating Mount Mazama, making this the oldest lava exposed in the caldera. 17. Sun Notch--This cross-section of a glacially scarred trough is located on the caldera rim. (Kerr Notch anci Munson Valley are also evidence of glaciers that draped Mazama's long slopes, some extending as far as seventeen miles toward the valley.) 18. Godfrey Glen and Colonnades--With the Pinnacles, this area ranks as the most significant feature along park roads other than those along Rim Drive. It is composed of fossil fumaroles marking the site of hot gasses that rose through the glowing avalanches that once filled the canyon. 19. Union Peak-- Its summit is an old cinder cone which grew on top of an old shield volcano. 20. Llao's Hallway--This 125-foot-deep gorge was cut through pumice material by stream erosion. It is located on Whitehorse Creek, a tributary of Castle Creek and once contained a trail leading through narrow passages to numerous cavelike amphitheaters. In addition to the geological features of the park there are several ecological communities of importance within its boundaries. These include Boundary Springs near the northwest corner, Sphagnum Bog and Thousand Springs along the western boundary, and some specific areas within the caldera walls of which Wizard Island and the Phantom Ship are the most outstanding. Three forest types are dominant within the park. These are the ponderosa pine at lower elevations, lodgepole pine extending from 5,500 to 6,500 feet, and mountain hemlock which is characteristic of the higher elevations. Also present in the park are Douglas fir; western white, 7.