Sea Level Processes and Effects of Sea Level Change

When studying sedimentary rocks on land, the first question a geologist will ask is whether the sediment was laid down above or below sea level, that is, whether or not it is of marine origin. For marine sediments, the next question usually is about the depth of deposition, that is, about the position of sea level relative to the sedimentary environment. On the present sea floor, depth of deposition rather dominates the major facies patterns of the material accumulating on it: the size distributions of clastic sediments, the chemistry of biogenous and authigenic matter, the distribution of benthic organisms. For the past, sea level fluctuations, on scales between thousands and millions of years, dominate the calendar of geologic history (Fig. 5.1).