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:
As the sea-floor spreads apart at a mid-ocean ridge, new sea-floor is created. This theory helped to explain the theory of plate tectonics. Earth's crust and part of the crust of the upper mantle broke into sections and could move. Convection from the inside of the Earth helped the plates move.