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How many major sea-level rises and falls occurred during the Cretaceous Period?

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Cretaceous paleogeography — Cretaceous Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Cretaceous Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

Detailed studies of the Cretaceous Period indicate that there were between 5 and 15 distinct episodes of rises and falls in sea level.1

These fluctuations were a significant factor in the period's paleogeography, as sea levels were generally much higher than they are today—roughly 100 to 200 metres (330 to 660 feet) higher during the Early Cretaceous and approximately 200 to 250 metres (660 to 820 feet) higher during the Late Cretaceous. The lack of a synchronous record for these sea-level changes across different regions is often attributed to the concept of geoidal eustacy, which suggests that as Earth's continents shifted, the oceans bulged in various locations to compensate, resulting in sea-level variations between different ocean basins.1