Simple. Air has mass. And if air has mass it also has weight. You can feel air when the wind blows. Or do an experiment. Weigh an empty container. Then pump it to a vacuum. Weigh it again. The difference is the weight of the air inside.
As you grow father away from the mid ocean ridge the rock is older as you get closer the rock is younger
Access Control Points
They are restrictions points that enforce regulations and guidelines on decontamination when exiting the sites and ensuring adherence safety standards when entering the site. The regulation are usually, as standard practice, conspicuously posted at the Access Control Points.
Access Control Points are usually set up at the periphery of the Exclusion Zones, and ideally, there should be a separate entrance and exit Control Access Point.