I showed up to the interview dressed to the nines, post double shot latte, and mentally prepped only to be ushered to a hallway lined with chairs and a dozen other potential applicants already waiting their turn. I knew I needed something to make me stand out if I had any chance of securing the job.
Answer 1: At plate boundaries where sea-floor spreading occurs, magma wells up to fill the space created by the plates that are moving apart. Check out this United States Geologic Survey (USGS) educational animation to see visually how it works:
1) types of boundaries between lithospheric plates; 2) features of the ocean floor; 3) the concept of sea-floor spreading; and. 4) the nature of the Earth's magnetic field and the fact that it has reversed its polarity many times in the past.