I’m not proposing this as an actual solution, it’s just a dumb idea. But if we dug a huge, wide hole at the bottom of the ocean, or maybe widened the Mariana Trench or something, could that extra space make the sea levels drop enough to keep the land from flooding?
It’s “dikes” in this case, and yes, you could use the stone for dikes or levees, but since most of it would be sedimentary rock I’m not sure how well it would work for the purpose: most sedimentary rocks are rather porous.
Oh whoops, thanks for the correction!