It is constantly being produced at the bottom of the oceans in places called mid-ocean ridges undersea volcanic mountain chains formed at plate boundaries where there is a build-up of ocean crust.
(It; is being produced; L:at the bottom of the oceans in places; T:constantly) (places; called; mid-ocean ridges) (undersea volcanic mountain chains; formed; L:at plate boundaries)
It places undersea volcanic mountain chains
is being produced called formed
L:at the bottom of the oceans in places T:constantly
mid-ocean ridges
L:at plate boundaries