tidal systems
Post on 27-Nov-2014
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Tidal Systems
Tidal flats represent the land area covered by sea water during high tide and exposed to the air during low tide.
Photo by W. W. Little
Oscillation (symmetrical) Ripples
Because of bi-directional flow, symmetrical current ripples are very common tidal structures.
Photo by W. W. Little
Flat-topped Ripples
Tidal ripples are often flattened as their tops are planed upon reversal of flow direction. In some cases, a small flap of sediment will extend away from the crest toward the trough in the direction of the reversed flow.
Photo by W. W. Little
Photo by W. W. Little
Flaser-bedded Mud
Because of highly variable energy conditions associated with tidal flow, flaser bedding in the form of clay drapes over silty sediment is common.
Photo by W. W. Little
Photo by W. W. Little
Interference Ripples
Surface ponding can lead to the development of oscillation ripples.
Photo by W. W. Little
Herring Bone Cross-bedding
Photo by W. W. Little
Dessicated Mud
Dessication cracks in mud can form during low tides.
Photo by W. W. Little
Burrowed Mud
Vertically-oriented burrows are common as organisms surface to feed during high tide and return to the subsurface for safety at low tide.
Photo by W. W. Little
Photo by W. W. Little
Root Casts
Salt tolerant vegetation, such as mangrove, commonly grow on tidal flats, causing bioturbation through root growth.
Photo by W. W. Little
Tracks
Animal tracks, including migratory trackways, are common on tidal flats.
Photo by W. W. Little
Photo by W. W. Little
Tidal Channels
Much of the drainage on a tidal flat enters the sea through a highly complex system of tidal channels.
Photo by W. W. Little
Photo by W. W. Little
Photo by W. W. Little
Photo by W. W. Little
Algal Mats
Algal structures are common features in tidal zones.
Photo by W. W. Little
Photo by W. W. Little
Photo by W. W. Little
Large-scale Architecture
Tidal deposits are characterized by horizontally-laminated mud with interspersed sand- or mud-filled channel forms.
Photo by W. W. Little
Photo by W. W. Little
Tidal deposits are often “bundled” into sand/mud couplets, related to annual neap/spring tidal cycles.
Tidal Bundles (parasequences)
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