An ash plume from an erupting glacial volcano in Iceland continues to cause problems for airports worldwide. Ray Suarez reports from London on the dangers the volcanic ash poses for air travel.

For historical perspective on the Icelandic volcano eruption, Jeffrey Brown talks to Simon Winchester, author of "Krakatoa: The Day the World Exploded: August 27, 1883," about the massive 19th century eruption's impact on health, the economy and even art and…