Sheesh TB, read this again -
From wehappyfew's message 6:
quote:
All three types of sediment are deposited simultaneously in a transgressive sequence. The shoreline at a particular place and time is the basal unit of the TS. It commonly contains conglomerates composed of the underlying sequence, and is always unconformable to it. At the same time the Tapeats sandstone is being deposited, farther offshore the tidal and beach sands grade into the silt and shale of the Bright Angel shale, just like passive margins today. Farther still, the water is deep enough and far enough from siliclastic sources to allow carbonate platforms to accumulate, like the South China Sea, for example.
As eustatic sealevel rises, the entire assemblage migrates uphill. Shales are deposited on top of sand, lime mud on top of shale, while the new shoreline cuts into higher ground pC basement rock, creating more siliclastic source material for the whole system.
This verbally explains the methodology of stratagraphic succession about as good as can be done - short of having some nice diagrams.
As sea level rises, what is deposited in the deeper waters is now deposited in the newly deepened waters, on top of what was deposited in more shallow waters. This results in the transgressive sequence - shallow water deposits on the bottom, deeper water deposits on the top.
A sea level fall causes the opposite vertical sequence - deeper water deposits on the bottom, shallower water deposits on top. That is a regressive sequence.
Perhaps you need to visit your local geology department, and have someone diagram lateral sedimentary facies changes, and the resultant vertical columns for a transgressive sea, and for a regressive sea.
Moose
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