Grand Canyon layers don't support dating methods?

Factual Questions
1

I picked up this book that said the Hermit shale in the Grand Canyon showed no signs of erosion before the Coconino layer, which supposedly came 10 million years later.

Do these two layers indeed conflict with current dating methods? If so, what does this suggest, if anything?

I have seen many religious books over the years calling BS on the dating methods employed by scientists, citing things like polystrate fossils and such… honestly, is there any shred of truth to these radical claims?

Let’s get busy and get some ignorance ironed out here on this annoying topic once and for all, what’dya say?!

2

Any shred of truth?

No.

Willfull misunderestanding and ignorance?

Yes.

One possible reason why a layer might show no signs of erosion is that another layer was deposited immediately on top of it. If the new layer was eroded completely away, then replaced by a newer layer, the dates on two succesive layers would have a gap.

Another explanation I can easily see is that depostion of new material at that site stopped for 10 million years, while it was protected from erosion underwater. Or some combination of both scenarios.

Failure to even come up or consider those two simple explainations is the willfull ignorance part. I’m not a geologist, but it didn’t take me long to come up with an explaination.

3

I am not a geologist.

If the deposition had been continuous, I see no reason why there had to be any sort of erosion at all.

4

“Polystrate fossils” is the fundamentalist term for such pedestrian occurrences as petrified plant roots showing up in many different strata. Of course they do - the roots grew down through the soil, into older layers.

5

Geologist checking in - although I admit it has been a few years since it was my profession.

Maybe it is me thinking this has got to be more complicated than it is, but I am afraid the extract you quote does not give us enough information to make it clear what the problem is. Can you clarify or link?

Are they saying there is this Hermit shale, then a ten million year gap in the record, then the Coconino layer? If so, they can only have estimated that from finding another stata elsewhere that is missing from the site in question. The reasons could be:

  1. That it was laid down and then eroded prior to the deposition of the Coconino (called a nonconformity or unconformity depending on stuff I will not go into)

  2. That it was never laid down at this site at all (a disconformity) in which case other stats may be thicker than elsewhere (as they were being laid down instead of the mystery “missing” rock due to conditiions differing between the sites)

  3. A combination of the two.

  4. There is confusion about the exact stratigraphy. This is not that uncommon

  5. They have got their facts wrong or are deliberately misleading you.

I have read no religious books calling BS on geological dating methods. Scientists are actually already very good at calling BS on theories that the evidence is against - it is how they make their name. The theory of stratigraphic progression (younger on top of older rock) is pretty much the basic foundation the whole of geology and archeology, and I am unaware of any mass of evidence that undermines it.

Science does undergo radical revolutions of thought, a good theory always has it’s day, but there usually a mass of unexplained or contradictory evidence (often from different sciences) that prompts such revolutions. The last for geology was plate tectonic theory, which was out there for ages but resisted for ages on the basis that nobody would believe that the continents could be mobile and the plates were undergoing continual creation and destruction (by massive geological forces - not theoretical deities). “It was against common sense!” - the trouble with common sense being that is it remarkably uncommon.

6

Here is an example of the religious:

http://www.icr.org/pubs/btg-b/btg-081b.htm

Here is a rebuttal:

http://www.cs.colorado.edu/~lindsay/creation/polystrate.html

I have read these, but I can find so little other information, it would help if an expert could outline why it doesn’t matter that dating methods say one thing, but a tree reaching up through millions of years of sediment is staring them right in the face?

I have noticed that some of the religious sites try to explain some things with the Flood, while others just argue simply for a younger Earth. Just thought I would point that out.

7

More Grand Canyon info: A Criticism of the ICR’s Grand Canyon Dating Project Talkorigins.org also provides a link to some feedback from Answers in Genesis on this page.

BTW - “www.talkorigins.org” takes one to the Talk Origins website. The domain “www.talkorigin.org” takes one to “Jesus Christ Saves Ministry.”

8

I say it would help me address the main issue in your OP if you would give me more detail so as to judge the relationship the between your Grand Canyon Hermit Shale and your Coconino deposit. On what evidence, are they saying that “lack of evidence of erosion” is a problem? Lack of erosion is common, erosion is common, gaps in the geological record are common for a variety of reasons. What is “this book” you picked up? What scientific papers do the authors cite? Help me to help you.

Instead we are off in search of “polystrate fossils”. OK I have read both links and the rebuttal seems pretty clear. There is no conflict. The fossil trees do not reach “up through millions of years of sediment”. The short summary is a good, well, short summary:

followed up in the main article by examples including

and finishes with

The guys at the ICR are turning a Nelsonian eye to the fact that millions of years can pass in one geological environment to deposit only thin strata, whilst ten of meters of geological record can be laid down almost overnight. For example in the case of catastrophic turbidity currents sweeping down the continental shelf:

http://members.aol.com/jtankard/ocean/turbiditycurrents.html

I do not know how you took away your interpretation from the souces you are cited, unless you are perhaps reading them with some preconceptions in mind.

I recall for somewhere that there is actually *some * evidence for a “Noah’s Flood”-like event I believe but (before anyone gets a hard-on) not on the biblical scale, extent or timeline. As a consequence I have not taken any special geological interest in it, any more than any other irregular catastrophic geological event which en mass makes up the science.

Happy to go back to your Hermit Shale problem, if problem it proves to be for, so far intact, standard stratigraphical theory…

9

This whole issue illustrates a complete misunderstanding and/or willful distortion of sedimentary processes by creationists.

One of the first principles that is extremely important to understand is that sedimentation in any one location is a fundamentally discontinuous process. In order to be able to deposit sediment, you need three things: 1) a source of sediment; 2) a means of transporting that sediment from its source to a given location; and 3) space to deposit the transported sediment. The variability of these three items in any one location will determine the completeness of the sedimentary record there.

For example, let’s say you can have a source for sediment and a means to transport it, but there’s no space available for a period of 500 years in the spot you’re interested in. The sediment will then be carried on to another location (a process called sedimentary bypass), and your spot will have no sedimentary record of that 500-year span, i.e., it experiences a period of non-deposition. Assuming that there is space available for a sedimentary deposit, then fluctuations in the amount of source material available and/or transport means will lead to more or less sediment being deposited at different points in time - that is, the rate of sedimentation does not stay constant over time.

And of course, erosion also plays a major role in the development of the stratigraphic record. Sediments or sedimentary rocks can themselves become sources of sediment for younger deposits through the erosional process, and thus play an important part of the rock recycling process in the Earth’s crust. In the process, you can’t help but erase the sedimentary record in one location while creating a record in the new. Erosion can also make space for those new deposits to accumulate - canyons, valleys, lakes, and other depressions can become filled over time.

Now, if you have consecutive sedimentary layers that are undeformed, it can become rather difficult to determine where erosion has affected the completeness of the rock record. That is particularly true in very fine-grained rocks like the Hermit Shale, because they do not have readily visible beds (more likely laminae just a few millimeters thick at most) that would make the results of regional-scale erosion obvious. That’s the point at which dating methods such as biostratigraphy come in handy for constraining the age of the rock. The 10 million year gap between the Hermit Shale and the Coconino Sandstone would have almost certainly been determined that way.

W/r/t the issue of fossils sticking up through younger layers: There is a process called differential erosion, which results in a rock being weathered and losing material in an uneven fashion. This typically happens when the composition of the rock is not uniform, either in terms of mineralogy (different minerals have differing levels of resistance to erosion) or grain size (smaller grain sizes tend to be more easily eroded). In the case of the “polystrate” fossils, all you need is for the fossil to have been replaced by a mineral that is more resistant to weathering than the material it is surrounded by. (The process of fossil mineralization can be complex and gets into details of chemistry that I don’t have space to describe here.)

With petrified trees, for example, the tree has commonly been replaced by silica (quartz) that is more resistant to erosion than the volcanic ash deposits around it, so it is possible to exhume the fossilized tree at least partially. At any rate, the end result is that you have a fossil tree sticking up out of its original deposit, and in a position now to be buried by younger sediment. How much younger that new sediment is turns out to be depends entirely upon the three criteria I listed above: sediment source, means of transport, space for deposit. It is in fact entirely possible to have a landscape that experiences a rate of new sedimentation of a meter or less over a total of millions of years - vast portions of Australia are a perfect example of a landscape that has hardly changed over the last several million years. If you now cover the fossil tree with more sediment - gradually over a period of years or through a flash flood, doesn’t matter - you will have something several million years old sticking up into much more recent sediment. There is no problem reconciling the age of the fossil tree with the younger sediment that it protrudes into.

Now, just imagine that the process I’ve just described happened 20 million years ago, so that even the younger sediment cover over the tree has been lithified (turned into rock). Why would you now interpret this process to mean that there is something wrong with the age determination of the rocks with respect to the fossil tree?

10

From hauss,

You want Geology links?
I got your Geology right Here

Here’s a good basic discussion: Geologic dating 101

You can even Interact with current theories (these PBS guys are pretty cool).

And scientists are even looking into the whole Flood thing too.

For further inquiries; Here is a list of Creationist claims their rebuttals.

Your Grand Canyon one in particular.

11

oops, that second to last line should read “…and their rebuttals”

So much for my credibiliy :slight_smile:

12

I am a professional geologist, but I have no idea what this post means. Could someone provide an actual link or a brief summary of this supposed mystery? As far as I can see, there is a layer of sandstone on top of shale. That doesn’t present any difficulties to me :confused: