1. Deltas and Estuaries

2. Carboniferous delta channels of Western Ireland, cliffs of Moher

3. Architecture is governed by tides, wave activity and the degree of clastic input from rivers. In microtidal environments with low wave energy “birdsfoot deltas” such as the Mississippi can build up due to local sedimentation and lack of reworking. In these settings sedimentation is concentrated close to the distributaries, although these switch around on 10s of yr. scale as sediment builds up in one area, making other basins more advantageous. Between the levee-defined channels sedimentation in marshy bays is quiet and fine grained. Break-out of levees during flood stage leads to infill of these bays so producing fining-upward sequences that are topped by muddy soil horizons.

4. In area of low tide but high wave activity, e. g
In area of low tide but high wave activity, e.g., Indus and Niger a rounded delta front is built up. Many modern deltas are in a drowned state today because post-glacial sealevel rise. High tidal activity results in deep embayments in the delta front. The deeper water area in front of a delta is marked by slumping and soft sediment deformation. Muddy layers can be reactivated as diapirs around which later sedimentation is diverted. Ancient analogue is the Carboniferous (Pennsylvanian) deltas of British Isles.

5. Deltas in continental margin stratigraphy

6. Delta classification scheme

7. Delta types

8. Indus Delta - drowned wave dominated

9. Yukon Delta

10. Mississippi birds foot delta, river dominated

11. Mississippi Delta - block model

12. Mass wasting on delta fronts

13. Mississippi bay fill model and example

14. Mississippi bay fill stratigraphic cross section

15. Bay filling deltas - stratigraphic model

16. Levee breach and bay fill, Mississippi

17. Breached levee results in infilling of inter-distributary bays

18. Mississippi River - sea-level response

19. Switching of Mississippi delta in recent geologic past

20. Cross bedded channel sandstones in Jurassic delta sandstone, UK

21. Overbank sands, Jurassic UK

22. Root bed and paleosol in interdistributary overbank sediments

23. Jurassic delta channel of NE England

24. Flame structures, water escape

25. Fossil wood in channel sandstone

26. Load casts in channel sandstones

27. Channeled and climbing rippled sands, Jurassic UK

28. Irish Carboniferous, bottom feeding traces

29. Estuary model

30. Yangtze Estuary

31. Wave dominated river mouths

32. Estuary tidal bars - stratigraphic model

33. Pre-flood estuary

34. River in flood

35. Coastal bar starts to reform

36. Coastal bar reforms

37. Vegetation reforms, system stabilizes