Biostratigraphy & Faunal Succession

Long before Darwin it was known that there is predictable order to the fossil record. All life does not appear in the same layer, but in different layers (strata). William Smith was the first one to discover and describe this in the late 1700s to early 1800s. He made one of the first geologic maps. During construction work in England he noticed that different types of fossils are found in specific strata, and this can be used to identify location and correlate rock units.

He made one of the first geologic cross-sections

He introduced a unique color-coded system to distinguish different layers that is still used today.

Each color represented a different rock layer

And he observed that specific types of fossils were confined to specific types of layers

So once again, this is the basic pattern of the fossil record we observe. Instead of all life confined to one rock layer, we observe *faunal succession,* where different types of life are confined to different rock layers in a predictable order. William Smith was one of the first to observe this, and he is often considered the "father of biostratigraphy." Here are some of his diagrams (which he color-coded to match the colors he used on his geologic map). Starting at the top of the fossil record (the "London Clay"), and going down we see different types of marine organisms are confined to different strata (today, these are called "biozones").

-----["Top" of Fossil Record: Cenozoic]-----

-----["Bottom" of (Mesozoic) Fossil Record]-----

*Faunal succession is the most fundamental observation/data of the fossil record. And one of the key takeaways from the succession of different marine biozones that William Smith discovered and observed is that life on the bottom of the ocean has not been the same type of life throughout earth's history.

Fascinating and it shows for how long these things have been known.

On the subject of sedimentary rock strata, is it possible to show that under no circumstances would different types of layers have formed in the order we see if all the material involved had 'settled' at the same time as certain Creationists claim?

That's to say the material that makes up sandstone is of different density (or so I assume) to that of mudstone or shales which are different again from chalk and limestone. If these materials were left to precipitate to form layers would they do so in the order we see?

I have a feeling there are actually layers of more dense material overlying those of lower density, which we wouldn't expect if the material for all strata had been present at some point in the past.

Most of the major strata sequences (megasequences) are a result of rising (transgression) and falling (regression) sea level. We can picture higher energy sand environments that are nearshore, then mud/shale is further off shore in lower energy environments past the wave base where it can settle out, and limestone further offshore beyond that.

When sea level rises, those environments shift and stack on top of each other, giving a transgressive sequence (sandstone-shale-limestone) of strata with sandstone on the bottom and limestone on the top. With a regression, this sequence is reversed, giving limestone-shale-sandstone.

So while all the sediment for the entire geologic column wasn't available at the same time, in the example you give of coarsening upwards, the material can exist at the same time (but in a different environment) to give a limestone-shale-sandstone sequence when sea level falls (as the shoreline retreats the sandy beach gets deposited on top of the shale and limestone to give a sequence like the one you are describing).

*On a side note, the 'settling' out you allude to is indeed problematic, because the finer grained materials (like mud shale and lime/carbonate) need low energy environments to settle out. One need only think of a glass of water with dirt suspended in it. That dirt will settle to the bottom eventually (after a day or so), but only if the water is not stirred or agitated. The problem is that about 60% of the fossil record consists of fine grained sediments like shale, deposited throughout the fossil record, which is difficult to settle under a catastrophic flood event model.

In terms of interpretation or explanation, and that's what we're trying to eventually get to: how do we interpret or explain this succession of fossils---the fact that specific types of fossils are confined to specific strata (rock layers) and these form a predictable sequence (*faunal succession*)? 

EVERYONE must account for this basic data of the fossil record. So what are some possible ways to interpret or explain this data? Well, laying aside the strength of a given interpretation/explanation, and just considering the prima facie possibilities, I can think of three possible explanations for why the fossil record appears the way it does:

(1) Evolution 

(2) Progressive Creationism 

(3) Flood geology 

The next step is then to consider which interpretation/explanation is best supported by the evidence. But of course we can't even get some people to acknowledge the undisputed observational data of fauna succession!!!

It's not strictly relevant to this subject but the question I was pondering was whether layers of all the different rock types found could possibly have been formed the way we see if, as some Creationists believe, they had all been deposited at the same time?

If all the loose material that constitutes sedimentary rock formations had been in existence and was churned up by some catastrophic event (the Flood) and then settled to the sea floor, would it resemble what we actually see? I very much doubt it would.

The argument that T_M makes is ridiculous I know because the material that makes up sedimentary rock strata was laid down over many millions of years but the order in which the different rock types were deposited would seem to give the lie to his claim if nothing else.

Yes, there are lots of contradictions and problems for a flood model. In answer to your question, in totality (the sum total layers of rock strata as we see them), no. Parts of what we see are compatible, yes. For example, we do see major sea level rises evidenced in the record (so things like transgressive sandstone-shale-limestone sequences are compatible with a flood). Problematically, though, at no time do we see sea level rising enough to cover the entire earth and all land masses.

Also, I should point out that creationists don't technically believe all the rock layers were deposited at the same time. They still accept that the rock layers were deposited in the order we find them, they just think the timescale is compressed. But it is very difficult to compress that much deposition into a year. Then there is the problem of succesive stacks of slow-growing reefs and stromatolites that simply can't be compressed into a one-year time frame. This is one of the problems YEC flood geologist Ken Coulson talks about in part 2 of his video that I posted.

Bioturbation is also a problem, when, for example, different marine organisms burrow into the ocean bottom sediment and create vertical and horizontal traces and 'churn' up the sediment. It takes time for organisms to do that. 

That time becomes exponentially problematic given the bioturbation we find at *thousands* of different stratigraphic horizons, where the ocean bottom gets churned up, and then that is buried and preserved, and then the sediment atop that gets churned up and buried, and so....thousands of times we observe going up through the fossil record. It's difficult if not impossible to compress into a one-year time frame.

Then there's the evidence of slow deposition. NO, NOT "uniformitarian assumptions" that it is slow. Evidence for slow deposition that even creationists recognize is problematic. I added to my post #3 above about this to the "settling" you alluded to. I will recopy and paste again here:

*On a side note, the 'settling' out you allude to is indeed problematic, because the finer grained materials (like mud shale and lime/carbonate) need low energy environments to settle out. One need only think of a glass of water with dirt suspended in it. That dirt will settle to the bottom eventually (after a day or so), but only if the water is not stirred or agitated.

The problem is that about 60% of the fossil record consists of fine grained sediments like shale, deposited throughout the fossil record, which would be difficult to settle out during a catastrophic flood event. One would expect such fine-grained sediment to stay suspended in water during a catastrophic flood (like the glass on the left), and to only settle out at the end of the catastrophic flood; not deposited *throughout/during* the catastrophic flood.