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

More Questions:

What is the only pasta to eat for good luck on New Years Day, according to Sicilian tradition?

What shape is the scar on Harry Potter's forehead?

During what war was the novel "The Last of the Mohicans" set?

What was renamed to Ho Chi Minh City in 1975?

Diamond Head is a popular surfer destination off the coast of which US state?

In what Australian state would you find Parkes?

What city named its airport after Charles de Gaulle?

In 2006, David Bowie was awarded a Grammy award for what?

Who are the creators of the TV show "Seinfeld"?

Lock, Shock and Barrel were characters in which Halloween film?

What H-word means designing, displaying and describing coats of arms and badges?

Where did two lanterns historically hand on the night of April 18, 1775?

In June,1974, Isabel Peron was sworn in as the first female president of what country?

Tim McGraw and Faith Hill won the Academy of Country Music’s very first Vocal Event trophy in 1997 for what song?

What river separates the cities of Detroit and Windsor?