Seafloor spreading at midoceanic ridges is how scientists first discovered the periodic reversal of what?

More Questions:

What single initial is used for the real-life director of Britain's M16?

How old was the Elephant Man when he died?

In the standard Monopoly game, what place will you land on if you roll 9 when on Park Avenue?

What is your occupation if you are sometimes referred to as an apiarist?

In the computer world, does the abbreviation DOS stand for?

Which famous composer wrote the opera "Carmen"?

Which US state is nicknamed the "Gem State"?

What is the second largest state in the US?

What kind of animal was the now extinct Dodo?

In The Simpsons, what is the name of the baseball bat Homer makes himself?

In the 2003 film "Love Actually', who played the role of Billy Mack?

What is the name of the last human city in the movie "The Matrix"?

What record company was founded by Berry Gordy Jr. in 1959?

In his Snake Plissken movies, what kind of snake is Kurt Russell's stomach tattoo?

What animated TV show's characters watch a cartoon with "Terrance and Phillip"?