What West African ruler made a pilgrimage to Mecca? What were some of its effects?

Gold is not now being extracted from seawater. why not? a. it would be too disruptive to marine life to develop any marine mineral resources b. there is no gold in seawater c. we don't know how to extract minerals from seawater d. it would be too costly and difficult to separate the small amount of gold from the very large amounts of halite and other minerals

Which volcanic eruption caused the most deaths

Where is the world’s shortest commercial runway?