11: Sea Level
In the simplest sense, sea level is the elevation of the surface of the ocean. But when we think about it in the geologic sense, things quickly become more complicated as we must consider variations in space, changes in time, and the complex interactions between the surface of the ocean, the Earth's crust, and the rate at which sediment is supplied to an area. In this chapter we will briefly explore all of these topics and think about how they are preserved in the geologic record.
- Explain what happens during transgressions and regressions.
- Define water depth, eustatic sea level, and relative sea level.
- Explain how tectonism and eustasy interact to cause increases or decreases in relative sea level.
Chapter thumbnail shows a relative sea level curve ( Page Quinton via Wikimedia Commons ; CC BY-SA 4.0 ).
-
- 11.2: Sea Level Terminology
- Clear terminology is an important precondition for a meaningful conversation about "sea level". Water depth is an instantaneous, location specific measurement of the distance between the water surface and the sediment surface. Eustatic sea level is the distance between the center of the Earth and the sea surface. Relative sea level is the distance between a local datum and the sea surface; it is a function of tectonism and eustasy and can be tracked through time.