Nerves rise ahead of Jerome Powell's keynote speech at Jackson Hole, Wyoming

There've been sharp falls on Wall Street this morning ahead of a major speech by the chairman of the US Federal Reserve Jerome Powell. He's begin speaking early tomorrow morning Australian time from Jackson Hole, Wyoming - and every word will be scrutinised for signs about the direction of US interest rates. But what the fascination with Jackson Hole - normally associated with fly fishing and the Wild West? Peter Ryan takes a look