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

More Questions:

In the song Santa Claus is Coming to Town, what does Santa know?

What does "Flotsam" describe?

Which literary work's title character is named Henry Higgins?

Alex Raymond created which comic strip character in 1934?

What year was the opera "Death in Venice" first performed?

Who was Humbert Humbert's obsession in the novel "Lolita"?

The Arkansas River flows into what river?

In what US states would you find Pikes Peak?

Whose second album was the chart-topping "No Need to Argue"?

What day of the week do the Bangles wish it was in "Manic Monday"?

Who played Jim Phelps in the 1996 movie “Mission Impossible”?

Canadian Prime Minister Lester Pearson won the Nobel Peace Prize for defusing what world crisis?

Which holiday replaced Dominion Day in Canada?

What short name does Dana use to refer to her son in the comic book series "Revival"?

What 2015 film broke over 40 box office records upon release?