There are also lesser
structural base levels where erosion is delayed by resistant rocks.[1] Examples of this include
karst regions underlain by insoluble rock.[7] Base levels may be local when large landmasses are far from the sea or disconnected from it, as in the case of
endorheic basins.[1] An example of this is the
Messinian salinity crisis, in which the
Mediterranean Sea dried up making the base level drop more than 1000 m below sea level.[8][9]
When base levels are stable or rising rivers may
aggrade.[12] Rising base levels may also drown the lower courses of rivers creating
rias. This happened in the
Nile during the
Zanclean flood when its lower course became, in a relatively short time, a large estuary extending up to 900 km inland from the Mediterranean coast.[9]
Base level change may be related to the following factors:
^Chorley, R.J. (1973). The History and Study of Landforms or The Development of Geomorphology. Vol. Two: The Life and Work of William Morris Davis, Methuen.
^Whipple, Kelin X. (2004). "Bedrock channel". In
Goudie, A.S. (ed.). Encyclopedia of Geomorphology. Routledge. pp. 81–82.
^Spotila, James A. (2004). "Crustal deformation". In
Goudie, A.S. (ed.). Encyclopedia of Geomorphology. Routledge. pp. 201–203.
^
abcKoss, John E.; Ethridge, Frank G.; Schumm, S.A. (1994). "An Experimental Study of the Effects of Base-Level Change on Fluvial, Coastal Plain and Shelf Systems". Journal of Sedimentary Research. 64B (2): 90–98.
doi:
10.1306/D4267F64-2B26-11D7-8648000102C1865D.