1. Tidal Systems
Tidal flats represent the land area covered by sea water during high
tide and exposed to the air during low tide.
2.
3. Photo by W. W. Little
Oscillation (symmetrical) Ripples
Because of bi-directional flow, symmetrical current ripples are very
common tidal structures.
4. 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.
6. 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.
12. 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.
14. Photo by W. W. Little
Root Casts
Salt tolerant vegetation, such as mangrove, commonly grow on tidal
flats, causing bioturbation through root growth.
15. Photo by W. W. Little
Tracks
Animal tracks, including migratory trackways, are common on tidal
flats.
24. Photo by W. W. Little
Large-scale Architecture
Tidal deposits are characterized by horizontally-laminated mud with
interspersed sand- or mud-filled channel forms.
26. Photo by W. W. Little
Tidal deposits are often “bundled” into sand/mud couplets, related to
annual neap/spring tidal cycles.
Tidal Bundles (parasequences)