Rejuvenation may result from causes which are dynamic, eustatic or isostatic in nature. The lake was formed by tectonic movements and eustatic sea level changes. Eustatic rejuvenation relocates the mouth of the stream. This results in global eustatic sea level rise (fall) because the Earth is not expanding. The late Anisian saw a major rise of the global (eustatic) sea level. Global or eustatic sea level has fluctuated significantly over the Earth's history. Eustatic sea level rise caused flooding, which accelerated as the rate grew more rapid. This would alone give a eustatic rise in sea level should it melt. Both eustatic sea level changes and subsidence rates tend to be longer cycles.