Tectonics are not the only cause of altered ocean circulation. Polar ice is another one. Look at the events related to Drake's passage and the younger drias event at the end of the last glacial. They may cause more rapid climate change.
Superposition is the geologic principle which explains why the bottom stratum in a section of rock is the oldest. The word literally means placing one thing on top of another where the lower strata are the older.
