As most of us would likely guess, walking is the most popular physical activity in America. But people who walk for exercise do so at wildly varying speeds and intensities. Some stroll at a leisurely 2 miles per hour, which is low-intensity exercise. Others zip along at twice that pace or better, resulting in a sweatier workout.
Mummification is a process in which the skin and flesh of a corpse can be preserved. The process can occur either naturally, or it can be intentional. If it occurs naturally, it is the result of cold (as can be found in a glacier), acid (as can be found in a bog) or dryness.
In addition to the well-known mummies of ancient Egypt, deliberate mummification was a feature of several ancient cultures in areas of America and Asia with very dry climates. The Spirit Cave mummies of Fallon, Nevada in North America were accurately dated at more than 9,400 years old.