Describe and explain the cause and effects of sea level change on coastal landforms
The main effect of rising and lowering of sea level is the movement of the position of the coast. As sea level rises, the coastline is moved toward the land. Geologists refer to this movement as a transgression. Conversely, if the sea level drops, the coastline moves out toward the sea, or a regression. The effect of transgressions is most readily seen as the sea floods, river or glacial valleys, forming drowned valleys or fjords, respectively. Although not prominent on our coasts, this is a common feature on the East Coast of the United States. There are two classes of sea level movement, localized or eustatic. Localized sea level changes only affect a limited area of coastline and can be caused by tectonic movements or rapid influx (or removal) of sediment. Eustatic changes refer to the removal or addition of water to the entire global ocean system, thus lowering or raising sea levels worldwide. Eustatic changes are brought on by the removal and locking up of ocean water in glaciers, or by major plate tectonic movements causing changes in the volume of the ocean basins. One example of the latter is that during time of rapid sea-floor spreading, the spreading centers become warmer and rise, thus lowering the volume of the oceans.
The main effect of rising and lowering of sea level is the movement of the position of the coast. As sea level rises, the coastline is moved toward the land. Geologists refer to this movement as a transgression. Conversely, if the sea level drops, the coastline moves out toward the sea, or a regression. The effect of transgressions is most readily seen as the sea floods, river or glacial valleys, forming drowned valleys or fjords, respectively. Although not prominent on our coasts, this is a common feature on the East Coast of the United States. There are two classes of sea level movement, localized or eustatic. Localized sea level changes only affect a limited area of coastline and can be caused by tectonic movements or rapid influx (or removal) of sediment. Eustatic changes refer to the removal or addition of water to the entire global ocean system, thus lowering or raising sea levels worldwide. Eustatic changes are brought on by the removal and locking up of ocean water in glaciers, or by major plate tectonic movements causing changes in the volume of the ocean basins. One example of the latter is that during time of rapid sea-floor spreading, the spreading centers become warmer and rise, thus lowering the volume of the oceans.
