Explain how magnetic stripes on the ocean floor are evidence for seafloor spreading.

The magnetic stripes on the ocean floor was a theory that scientists created. It was said that the patterns of the rock, and we all know that the earth acts like a magnet (north and south poles). It was said that Earth's magnetic poles have reversed themselves many times during the Earth's history. 
The rock of the ocean floor contains iron. The rock began as molten material that cooled and hardened. As the rock cooled, the iron bits inside lined up in the direction of Earth’s magnetic poles.

Hope this helped :)
Have a great day 

Answerglycogen;

How many miles is each lap?