Which process continually adds new crust?

Sea floor spreading occurs at middle ocean ridges. It causes new crust.There’s a new ocean crust that is formed from volcanic activity. This will gradually move sometimes away from that ridge. This is the reason for continental drift as it relates to the theory of plate tectonics. The ocean plates will move back and forth and this causes tension that makes fractures to occur.

This force for seafloor spreading is caused by the tectonic plate, not the pressure of the magma. It seems that older rocks will be farther away and new rocks will be near the zone of spreading. It is still rather in the theory stage. The spreading rate can be either fast, intermediate, or slow. If it is fast the rate can be more than nine centimeters a year.