OK. Would it be feasible for a large, fast traveling interstellar body to pull a planet into an orbit closer to it's star? And in doing so, exert such forces that might cause an entire continent to collapse/sink? Thus raising the water 800+ meters in the process, and changing the balance of nature all over the planet (currents/tides/winds, etc all affected...and this continent would be in my currently blank portion of the map which is in the north of the planet.

Would a sudden shift in such a large piece of land (larger than antarctica) toward the planet's core be enough to cause a significant shift in a planet's orbit on its own?