until it's dis-proven, or until it is proven.

we have plenty of evidence of the movement of plates. we know where subduction zones are. what does it take to prove a theory if not repeatable tests/observations?

the large body of corroborating evidence (and ability to be dis-proven) is what makes it a theory

but we can't "prove" plate tectonics, because we can't directly observe what's going on the earth's crust over a period of millions of years

in scientific nomenclature, a theory is a very robust thing indeed

vs. the vernacular, where it isn't, e.g. "I have a theory that my cat vomits behind the couch after I give him ice-cream"

> we can't directly observe what's going on the earth's crust over a period of millions of years

Depends what you mean by “observe”. The parallel lines of reversing magnetic polarity that are embedded in the sea floor on either side of the great rifts are observations that demand explanation.

well that's easy to explain

the devil went over the seabed with a big magnet, to trick you

just like he concocted the entire fossil record, planet-wide rock strata, carbon 14...

(sarcasm, for the USians)