Geology- working up from basic principles.

...Example, your cat got a clever idea and decided to put the top on on the bottom.

Minnemooseus writes:Depicting a sedimentary basin as being like a steep sided bowl is highly inaccurate, although even legitimate geologic scientists do use vertical exaggerations in doing their cartoon diagrams. Also, it may well be that the basin is subsiding as it is being filled with sediment — What started as a dinner plate of sediment becomes more of a bowl of sediment. The sediment conforms to the bowl’s shape because it was warped as the bowl was warped.They seem to propose that sea transgressions and regressions are like water sloshing around in a bowl or tub. This is plain goofy. Then they somehow bring Mt. Saint Helens into the discussion, further raising the goofy quotient.They mention Walther’s Law, which is indeed a well-regarded principle of geologic sedimentary modeling. Essentially, Walther’s Law says that in a basin the coarsest sediment is deposited closed to the shoreline and the sediment gets progressively finer as you go seaward. This is because coarse settles faster than fine (try Googling Stokes Law).The processes behind Walther’s Law results in a fining upward sedimentary sequence for marine transgressions (the sea came in) and a coarsening upward sedimentary sequence for marine regressions (the sea went out). Just think of how the distance of a point from the shoreline changes in transgressions and regressions. In transgressions what was dry land becomes near shore shallow marine and what was near shore marine becomes further from shore deeper marine. For a regression, the opposite is the case.To elaborate — Pick point A on land. Just offshore the coarse sediments are being deposited and further out the finer sediments are being deposited. Such is probably a gradational change. Now as the sea comes in, point A is now near shore marine with coarse sediments being deposited. The sea comes in more, and point A is now further from shore and finer sediments are being deposited. The fines are on top of the coarse. The reverse is the case of a regressing sea — Then you get the coarse on top of the fines.Their flume modeling would seem to be much more a river model than a transgressing sea model. Even as a river deposit model, it is probably disconnected from reality and/or at least oversimplified.Concerning the original horizontalness or near horizontalness of sedimentation — Such is generally the case, although there are exceptions, the most prominent being the inclined crossbedding in ripples and dunes.Getting back to a marine transgression. Remember that these take a long time to happen, even in the geologic timeframe. Offhand, thousands to millions of years. Now let us just consider what is being deposited in the near shore marine environment — sand that becomes sandstone. The short and simple picture: A horizontal or near horizontal layer of sand is deposited, the sea comes in a bit more and another layer is deposited. Repeat step thousands to millions of times. What you get is a shingling of layers, each successive one a bit higher in elevation and extending a bit further upslope.The analogy: Lay a 4 by 8 sheet of 1 inch plywood on a horizontal surface. Lay another sheet on top, but offset it an inch in the long dimension direction. Repeat a thousand times. What do you get? A stack of a thousand sheets of horizontal plywood, which collectively forms a layer of wood with a 45 degree surface slope. The bottom sheet is the oldest (first deposited) sediment; the top sheet is the youngest (last deposited) sediment.Well, as is the general case, a picture might be worth a thousand words. But I have to do it in words. Hope this was of some enlightening value.

It implies that to an untrained eye, the strata would look like they are in lateral layers...

From what you are saying, it sounds to me like the layers are deposited horizontally just like we'd expect, but the depositional material changes as you move from the shoreline outwards.

...plus the scale measurements you provided...

This sort of deceptive misrepresentation by creationists hacks me off more than plain ignorance.

I've been doing some reading and from what I understand, a slope of 10 degrees or more would cause particles to roll down the slope and be deposited in a talus at the bottom, though I'm sure this is rather simplistic.

My sister-in-law is a geologist but she's in Iceland right now studying glaciers, LOL -- can't ask her.

I think I might still be misunderstanding this whole concept. I was imagining that when sediment washes from the shore, the sand lands closest to the beach, then finer particles further out, making a horizontal stratum with differing materials as you move out from the shore. Newer layers would be added on top of this. So the principle of original horizontality would apply as usual.

But this doesn't chime with Moose's initial post about this or other posts I've read on EvC, that say that heavier particles such as sandstone are deposited near the shore, while you need deeper water for the finest particles to settle out. This is surely describing a horizontal succession of different-sized particles (the equivalent of making the stack of plywood sheets, each offset a little in the same direction).

I found this diagram, which makes more sense to me. The timelines are marked vertically through the strata.