Coasts
Form of sediment is highly dependent on the effect of tides, wave
activity and degree of clastic input from rivers.
Microtidal coasts: Usually stormed dominated. Coastal areas are
dominated by sandy barrier island features, elongate parallel to the
coast. Length of island increases with decreasing tide strength.
Reworked rapidly during storms that cause breaks in islands and
wash over into the tidal lagoon. Storms are capable of washing
large volumes of sediments out on the shelf, producing sheets 510 cm thick and up to 50 km across. Inlets through island migrate
rapidly due to daily current activity, 10s of m per years. Sediments
fine rapidly offshore into shelf muds. Modern examples: Dutch
coast Texas Gulf Coast, Carolinas.
Irish Atlantic coast, dune fields
Macrotidal coasts: No barrier islands but instead tidal flats.
Sandy sediments develop wave ripple lamination, large scale
dunes around river estuaries. Mud flat develop sandy ridges
(Cheniers) where occasional storms activity sorts and reworks
the flat sediment. Reworking by burrowing organisms is
common. Current directions vary within the tidal zone
resulting in sands with cross bedding showing flow in two
opposite directions. “Tidal bundles” are formed in inter-tidal
zones, due to settling of mud drapes over sandy dunes and
ripples during the high tide. Spring and neap tides of varying
strength can be traced through the strength of development of
the tidal bundles. Shallow offshore is characterized by sand
ridges running parallel to the tidal flow. Modern examples,
English Channel, Bay of Fundy Canada, East China Sea.
Coastal zone
morphology
Beach erosion or sedimentation?
Makran coast, an
uplifting coastline
Coastal sedimentology-only for the dedicated.
Tidal ranges and coastal morphology
Barrier island response to sealevel rise
Tidal inlets, effect of tidal strength
Barrier island
response to storm
Barrier island-wash-over fan
Barrier island-inlet migration
Barrier islandsealevel
model
Barrier island-differing responses to sealevel change
Barrier islandstorm erosion
Galveston Island, map
Galveston Island,
barrier island
Beach progradational stratigraphy
Beach seasonal erosion example
Beach seasonal erosion model
Cape Hatteras, Barrier Island system
Chesil beach, England, a classic storm beach
Chesil beach,
England, high
wave energy coast
Texas
coast sediment
fining
offshore
Tidal dunes, Eastern England
Sandy tidal flats - North Sea coast of England, macrotidal
Tidal marshes - North Sea coast of England, macrotidal
Tidal flat sediment types - 1
Tidal flat sediment types - 2
Tidal bundles - tidal sedimentation
Tidal bundles - clay drape evidence of tidal sedimentation
Herringbone cross
bedding - tidal
sedimentation
Wave rippling-tidal flats