Mount Hood's last major eruption occurred in the 1790's not long before Lewis and Clark's expedition to the Pacific Northwest. In the mid-1800's, local residents reported minor explosive activity, but since that time the volcano has been quiet.
Signal Colors and Their Meaning. The colors used in today's signals are green, yellow, red, lunar, and white (remember, we're talking about signals in North America). The color of a signal tells the engineer what he has to do, the location of that color, determines the speed at which he is allowed to do it.We will get to the speed thing in a minute.he colors used in today's signals are green, yellow, red, lunar, and white (remember, we're talking about signals in North America). The color of a signal tells the engineer what he has to do, the location of that color, determines the speed at which he is allowed to do it. We will get to the speed thing in a minute.
The color redis a symbol to STOP, yellow is a symbolto SLOW, and green is a symbol to GO. Traffic signals rely completely on aperson's ability to memorize the colors and associate them withcertain functions. Other objects, or devices, also require colormemory in order to be highly effective.he color redis a symbol to STOP, yellow is a symbolto SLOW, and green is a symbol to GO. Traffic signals rely completely on aperson's ability to memorize the colors and associate them withcertain functions. Other objects, or devices, also require colormemory in order to be highly effective.