The most recent rise in sea level drowned many semienclosed coastal embayments producing estuaries in those that received sufficient freshwater to measurably dilute the encroaching seawater. Most of the basins were former river valleys carved during the previous low stand of sea level. Some scientists restrict the term estuary to submerged river valleys, but other coastal embayments that exhibit similar biological, chemical, geological, and physical processes are appropriately considered to be estuaries. These basins include fjords, bar-built embayments, and basins formed by tectonic processes (Schubel, 1971).
Submerged river valley estuaries are also known as ria coasts. The basins are commonly V-shaped in cross section, and the depth increases more or less uniformly in a seaward direction. Their configurations are largely inherited, produced by the rising sea coming to rest against landforms shaped by fluvial processes. They may be of either dendritic or trellis type. The...
- Schubel, J. R., ed., 1971. The Estuarine Environment: Estuaries and Estuarine Sedimentation. Washington, D.C.: Am. Geol. Inst. Short Course Lecture Notes, 324p.Google Scholar