On the Huon Peninsula of Papua New Guinea, a set of coral marine terraces grace the coastline. These are datable using U/Th methods, and have yielded good dates back to several hundred thousand years. One of these terraces 120 m above modern mean sea level is dated to be 80 ka. 

a) What is the long-term rate of rock uplift on this coastline?

b) What assumptions have you made in performing this calculation?