When a river flows over the earth and carves out a hole in the surface it makes a?

How did Switzerland get its name? What is the name of the arm of the Pacific ocean extending 100 miles into the state of Washington? What town in Canada has the highest annual rainfall? How many tourists visit the grand canyon every year? What ocean is 80 degrees north 80 degrees east? Who was the explorer who traveled through the Great Lakes area Lake Michigan Wisconsin and Illinois possibly reaching Lake Michigan? What side is the Euphrates on? How many trees have been destroyed to get mahogany trees? How many Indians were there at the 1st mission? Why does water boil at 71 degrees Celsius on mount Everest? Where was Ponce de León's Fountain of Youth said to be located? Why was the castle of good hope built? When does nigara falls freeze? Can women pray at the Western Wall? What is the bridge that goes from Manhattan to Astoria? What bus takes you to Drayton Manor from Glasgow? Who may be buried in Section 60 at Arlington National Cemetery? What state is west of the Mississippi river? What is the purpose for a concentric castle? Fun things to do with an 11 year old?