1. 3 principle mechanisms of deposition: currents, waves, and animal/sediment interactions

2. Waves & currents in storm dominated shelf:

storm surge: high water under a low pressure system

coastal setup: wind blows water up onto land

geostrophic current: bottom flow as water returns to sea from coast is turned by Coriolis forces to become parallel to land

long shore drift: sediment moved along the coast line by wave action.

3. Storm-dominated nearshore:

4. Relative vs. Absolute Sea level: Absolute sea level is global sea level, changed by a change of volume of water in the oceans. Affected by things like how much water is caught up in ice caps. Relative sea level is what sea level is doing locally due to a combination of global sea level and the subsidence (or uplift) of the seafloor.

5. Transgression & Regression

Click here for movie of a slow sea-level fall in an experimental basin.

Click here for movie of a fast sea-level fall in an experimental basin.

A. regression: shoreline migrates seaward due to: relative sea level fall, increased sediment supply

Walther's Law: facies that occur in conformable vertical successions of strata also occurred in laterally adjacent environments.

B. transgression: shoreline migrates landward. Due to: relative rise of sea level. If transgression is rapid, then waves can cut a scour surface (often referred to as a ravinement surface or a transgressive surface of erosion). Transgressive lag is the coarse material left on top of the ravinement surface. Rocks above this surface are deeper water sediments. Hence this surface can also be called a "flooding surface." As transgression continues the deposits above the transgressive surface show deeper and deeper water environments. At some point the transgression ends and a regression begins. The deposits, offshore, start showing evidence of shallower and shallower water. This change from 'deepening upward' to 'shallowing upward' deposits is called a "maximum flooding surface."

6. Tidal dominated shelf:

Click here to view time-lapse movie of ebb tide.

Click here for movie showing intertidal bars and channels.

A. Tidal bulges are due to moon,sun, earth alignment. Tidal bulge is lined up with sun on one side, and at the antipodal position on the back side of the earth. As the earth spins through the tidal bulge you get two high tides a day (and two low tides). When the moon, sun and earth are perfectly aligned (i.e. new moon and full moon phases) we get the highest high tides (= Spring Tide). When the moon is perfectly out of alignment (i.e. first quarter and last quarter) we get the lowest high tides (= Neap Tide).

Click here for a chart showing the harmonics of a month of tides (use browser back button to return).

C. A tidal bundle sequence, is when you see the fortnightly (i.e. two weeks) between, say, two successive spring tides. This shows up as a steadily decreasing current strength (from spring tide into neap tide) followed by an increase in tidal current strength (from neap tide to next spring tide). Since this takes two weeks and there are two high tides a day, tidal bundle sequences are a series of beds found in groups of 28 (14 days x 2 tides a day).

D. Tidal Flats:

Supratidal flat = always above mean high water (a mud flat).

Intertidal flat = under water 2 times a day (a "mixed" flat).

Subtidal flat = always below water (a sand flat).

E. Tidal Deltas: where tidal channels cut through barrier islands or spits delivering sea water from the open ocean to lagoons, sand gets carried in and out through these channels. As, say, sediment is moved into the lagoon during the flood tide, you build a small delta at the inboard mouth of the tidal channel = Flood tidal delta. During the falling, ebb, tide, you can build a channel at the seaward mouth of the tidal channel = Ebb tidal delta.