Deposition and Erosion of Sediments

I fear you have a very simplified view of what are sediment and sedimentary processes.

There are a large number of different sediment types and sedimentary environments. Vast amount of study time has been done on all this, ranging from using a microscope on up. Vast numbers of journal articles and thick books are the result. Whole university courses are devoted to specialized areas of sediments and sedimentation. And here we try to cover it all in an on-line forum.

Indeed, a long history of deposition and erosion, repeated over and over, may well be the route to what is seen in the end. The marks of erosion and/or non-deposition may be large (Grand Canyon) or they may be very subtle.

One example of a sedimentary environment is that of a river (referred to as the fluvial environment). In a modern river environment, the sediment of the river banks and flood plain continue to be re-eroded and re-deposited. What you see is the current (no pun intended) result, subject to further change. In either a modern example or an old now rock example, evidence of much of the process can be seen.

Concerning limestones: The geo-cliché is that limestones mean that nothing was happening. They are there because the was no tectonic activity in the area, and thus no detrital (fragmental) sediment was being brought in and deposited. They are the result of a very placid environment. Much of the limestone is directly or indirectly of biological origin - it is a graveyard of past life.

Enough for now. Follow up questions welcome. Fellow geologist are welcome to harpoon me.

Mellow Moose with a rusty geology degree

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Professor, geology, Whatsamatta U
Evolution - Changes in the environment, caused by the interactions of the components of the environment.
"Do not meddle in the affairs of cats, for they are subtle and will piss on your computer." - Bruce Graham

Depending on the environment, the degree of sediment reworking and movement can vary from little to none, to very extensive.

The previously mentioned fluvial environment is, of course, subject to massive reworking. Likewise a wind blown sand deposit (dune). A deep sea turbidite deposit, on the other hand, is much more isolated from erosional forces.

Even in the absence of current reworking, there is such a thing as biological reworking (bioturbation). Think of how modern sediments are being churned by the life forms present. On a pre-Cambrian field trip, the professor commented on how someone else had commented that the there present tidal deposits contained the best preserved tidal structures he had ever seen. The reason? No life was present to bioturbate the sediments.

A great example of the reworkings of sediments over a long time period, is found in quartzites (near 100% quartz sandstones). Not only is a lot of physical wear required to get rid of the other softer minerals, but the quartz grains themselves show a long history of wear. It take a lot of abrasion to round an originally angular quartz grain. Even more extreme is the example of quartz grains with abraded over growths. The grains were eroded and rounded and deposited and silica cemented into a hard rock. Then they were re-eroded, re-rounded, re-deposited, and re-cemented again into a new hard rock. Individual grains can be found, that show multiple cycles of this process.

One question that is rarely touched on is, if vast amounts of the sedimentary rock pile were deposited in the short period of "the great flood", where did these sediments come from? It is a similar problem to "flood geology", as to where did the water come from. While mainstream geologic theory has no problem with the sediment source, "flood geology" seems to have to produce the sediments from who knows where.

I once ran the "where's the sediments from" question past Tranquility Base. He proposed the concept of "catastrophic weathering". I likened that concept as being along the lines of two turtles having a catastrophic collision.

Moose

The only record we have of seas and oceans older than that is those that were pushed up by tectonic forces and became part of continents, such as large areas of Arizona.

I think you threw out a clinker here.

I think your sea deposits in Arizona are from sea transgressions onto the continents. The deposits were always continental, not from the ocean basins.

Example of oceanic ancient crust are the ophiolite complexes, such a found on Cyprus.

Moose

{Edited to correct spelling of "ophiolite". Ophiolites are off-topic here.}

Second edit: Nice ophiolite link

This message has been edited by minnemooseus, 03-17-2005 01:28 PM

This message has been edited by minnemooseus, 03-17-2005 01:34 PM

I'm probably the least powerful degreed geologist at this forum, as far as putting arguments forward. Indeed, many of the non-geo-degreed are stronger than me.

In addition, I'm pretty slow at preparing responses, and thus would not be the one to overwelm you.

I think we have gone away from the "Great Debate" being a judged debate, which is fine with me.

In the past, there often has been a parallel "peanut gallery" thread, where others comment on the "GD" topic. In a sense, the others are still participating in the debate, and as of the most recent "GD" the side topic has been prohibited until after the "GD" is completed. As a matter of fact, I think it was Adminnemooseus that suggested (and enforced?) this restriction.

Please start a Suggestions and Questions topic, if you wish to discuss a possible "Great Debate" topic further.

Moose

This message has been edited by minnemooseus, 03-17-2005 06:30 PM

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Professor, geology, Whatsamatta U
Evolution - Changes in the environment, caused by the interactions of the components of the environment.
"Do not meddle in the affairs of cats, for they are subtle and will piss on your computer." - Bruce Graham

1) Genesis in the Bible.

2) The creation itself, which in the case of the Earth's geology, is the Earth's geology.

You are dead set on sticking to Genesis, and your interpretations of Genesis. You are determined, in making your interpretations of your very limited knowledge of what the Earth's geology is, to make (2) conform to (1).

Moose

Added by edit:

JonF expanded on the above in his message at the Is Evolutionist Disparagement of Creationism Justified? topic. It better belongs in this topic, so I will quote it in its entirety.

JonF (with interal quotes from Faith) writes: You demand references for extremely reasonable scenarios that are beautifully consistent with the actual observable facts No, actually I politely asked for you to specify exactly what your vague generalities mean so I can determine if your scenario is reasonable and consistent with the observed facts. As I pointed out already, the formation of any significant portion of the Earth's sedimentary layers and/or fossil record in one diluvial event is an unreasonable scenario that is inconsistent with the observed facts. I alrady gave some references; I'll be glad to provide more on request. I note you didn't address any of the substantive points in my post, especially the fact (and the evidence for that fact) that devout Christian creationist geologists started with exactly your suppositions ... and discarded them because they were untenable in the light of observed reality. but you allow yourselves the air of certainty over deductions made from circumstantial evidence? A lot of what you think you so certainly KNOW from "science" is very likely to be overturned by the next investigator. Exactly what deductions from exactly what circumstantial evidence? Exactly what is likely to be overturned by the next investigator, and why? I suspect that your only evidence or "reasoning" for those claims is that you wish it to be so because you can't face the real evidence.

This message has been edited by minnemooseus, 03-21-2005 07:32 PM

Faith writes: Science is done by fallible humanity, and all the conclusions you think you have about the origins of the earth can claim no final authority. Genesis was authored by God and there's no "interpretation" that could change the straightforward descriptions of the creation of humanity and all things and the destruction of all in the Flood. Period.

Glenn Morten, elsewhere, writes: Thus was born the realization that there is a dangerous demon on the loose. When I was a YEC, I had a demon that did similar things for me that Maxwell's demon did for thermodynamics. Morton's demon was a demon who sat at the gate of my sensory input apparatus and if and when he saw supportive evidence coming in, he opened the gate. But if he saw contradictory data coming in, he closed the gate. In this way, the demon allowed me to believe that I was right and to avoid any nasty contradictory data. Fortunately, I eventually realized that the demon was there and began to open the gate when he wasn't looking.

The above was extracted from http://www.talkorigins.org/origins/postmonth/feb02.html, where Glenn Morton was awarded a talk.origins "Post of the Month".

My impression is that Faith is absolutely in the grips of Morton's Demon. Any further discussion with her is pointless.

Moose

ps: BTW, Page 1 of Google search for "Morton's Demon".