Two-thirds of China's vast territory is either mountainous or covered by desert. Every spring, windstorms come raging out of the mountains and cross the great deserts, gathering dust. A dense cloud of dust forms that is hundreds of miles wide. It is blown thousands of miles, traveling from the North Pacific to the Gulf of Alaska and from there moving south and then east. As the prevailing winds lose their velocity, dust particles fall from the cloud. It is believed that as much as 10 percent of the soil in Hawaii comprises dust particles collected from China's deserts and dispersed in the journey across the Pacific.