(Courtesy Oregon Timber Trail) 1  Since 1992, hikers have been able to traverse Oregon north to south using the Pacific Crest Trail, which traces the Cascades from the Bridge of the Gods to the California state line. This summer, you can finally bike across the state, from Hood River to the mines of Modoc County, Calif.
Definition: A delta wave is a type of high amplitude brain wave found in humans. Delta waves have a frequency from one to four hertz and are measured using an electroencephalogram (EEG). These brain waves are thought to emerge from the thalamus and are generally associated with slow-wave sleep (during stages three and four of the stages of sleep.
tidal wave the wave after the percussion wave on a sphygmograph recording; the second elevation of the tracing, preceding the dicrotic wave. ultrasonic w's waves similar to sonic waves but of such high frequency (20,000 hertz or higher) that the human ear does not perceive them as sound; see ultrasonics.