Why are such phenomena as hurricane katrina and rare earthquakes in regions where oil shale is fracked called "hundred-year" events?

The impact of a large asteroid comet with earth has been proposed to have caused the extinction of the dinosaurs. the impact site of this comet is in or near

Which feature of a map shows the relationship between a distance on a map and that distance on earth? key scale grid system compass rose

Which movement developed in the early 1900s and encouraged the nationalist spirit of africans throughout the world? a. african nationalist b. tribalism c. pan-africanism d. african union