Murray and bruce collaborated on six of these profiles, or silhouettes of the sea floor from six different expeditions. It's kind of like drawing someone's face from just a silhouette of their side profile. And as she was making these maps, Marie noticed something pretty big, like something spanning the entire length of the ocean. But it was also just very strange whenwe found the mountain ridge. And ten we fond the crack. The mid atlantic age is where the north american and urasian titonic plates are pulling apart from each other, which creates like a crack. Magma comes out and pushes these slabs apart, which then solidifies mountain ranges on either side