Fossils found spanning sedimentary layers?

[hackenslash]

Theropod submitted an excellent post at RDF about polystrate trees some time ago. The fact is that wood is a persistent material, which is why we use it for building. Think of all the buildings made of oak in the last 2,000 years that are still standing, such as the fabulous oak hammerbeam roof of Westminster Hall, built in the 11th century. They stand through several sedimentations, because they die standing up. That's all there is to it.

Edit:

You bet!

The problem, for floodites, is that there are DIFFERING situations under which polystrate trees are found.

Yellowstone National Park has these trees standing upright in successive volcanic deposits and not water borne sediments. Did the volcano erupt under water in separate events, and deposit the usual suspects? Water tends to not allow ash to form in the same form as that exposed to air, as current underwater volcanoes show a "smoker" characteristic devoid of this type of fluffy ash. Pyroclastic flows NEVER happen under water, and the Yellowstone fossils clearly record these events.

There is, then, another type, where sediments are laid down in multiple flooding events. There are extant situations where there very types of fossils are forming today. In oxbow formations, of normally slow moving rivers, high water events will sometime bury the root and a good portion of the trunk under a layer of sediment. Some trees, such as bald cypress, are very durable and can remain standing for a very long time after death. The sediment itself helps support the tree between depositional events. Even if a hundred years passes another flood can lay down a layer of differing sediment. This can be repeated several times. Also in coastal settings successive land settling events can form these fossils.

What the floodites fail to grasp is that these multiple layers all display indicators of separate events. A global flood would not show these differences as all the clastics would be mixed at the same rate and with the same contents. This form of fossil has been well understood for a very long time. John William Dawson explained this quite well in 1868. HERE is a good expose' on the subject.

Hopefully this puts this issue to rest, in your mind at least.

RS

[Faithfree]

Put's on my sedimentologist (sedimentry geologist) hat - they actually pay me to interpret this sort of stuff for a living.

Hi Bolero,

Plenty of good sources above; I'll just add a few more points here.

Here's a modern 'polystrate telephone pole' from the Mt Pinatubo area, formed very rapidly in the same way as as many fossil polystrate trees. While it may span several metres of strata comprising apparent different layers, all were deposited rapidly in closely spaced events - in this case floods following a volcanic eruption.

(http://pubs.usgs.gov/pinatubo/punong1/fig18f.jpg)

If you can understand the figure below you will understand why one the most common creationist geological arguments (that relating to depositional rates) is absolute nonsense. Note that the scales on the figure are logarithmic.

Sadler rates of sediment accumulation.jpg (89.54 KiB) Viewed 3222 times

(Source: Sadler, P.M., 1981, Sediment accumulation rates and the completeness of stratigraphic sections: Journal of Geology, v. 89.)
Analysis of many modern environments of sediment deposition shows an enormous spread of depositional rates when measured during short term events, i.e. deposition is often episodic. Much rapidly deposited sediment is subsequently eroded and there are typically long times of little or no activity between major deposition/erosion events. The rates of sedimentation quoted by geologists are the long term net accumulation rates (those appearing near the middle bottom of the diagram), which are much, much lower than the maximum possible rates of short term events in all environments. Creationists on the other hand fixate on the top left of this diagram, the short term high intensity events. They think if they can show that a few layers of rock were deposited very quickly (e.g. those with polystrate fossils) they can claim that all sedimentary rocks were deposited rapidly. Absolute bollocks, as demonstrated by observing deposition in the full spectrum of modern environments.

[Edit: I showed some photos I took of polystrate tree fossils in another thread a while back: http://rationalia.com/forum/viewtopic.p ... 71#p314271. These are in Jurassic volcanic sediments in New Zealand.]

[Bolero]

I guess I should have checked RDF and rationalia archives first. Everyone seems to have discussed this issue already.

[Randydeluxe]

As long as we never forget that a dead fish today doesn't sink - it floats!

[Gawdzilla Sama]

I guess I should have checked RDF and rationalia archives first. Everyone seems to have discussed this issue already.

All good, we haven't discussed or cussed it here yet.

[cowiz]

Polystrate tree fossils - it's a well known phenomena and in no way supports cretinist bollox

[Gawdzilla Sama]

Polystrate tree fossils - it's a well known phenomena and in no way supports cretinist bollox

Every one of their objections is based on ignorance or willful misrepresentation. It's just a matter of somebody who knows the topic looking at it for their carps to fail. This is the same with every conspiracy theory out there, as I learned dealing with Pearl Harbor Was a Trick loonies.

[Deep Sea Isopod]

As long as we never forget that a dead fish today doesn't sink - it floats!

I wondered why the bottom feeders were dying out.

[Reverend Blair]

Er...kind of a related question.

How do they tell if a fossil has moved up through layers?

I know the freeze/thaw cycle here can shift buried rocks upwards over time. Since the frost level is six feet, presumably it can move rocks that deep down. So can they tell if something has been shifted upwards in this way?

[Gawdzilla Sama]

Er...kind of a related question.

How do they tell if a fossil has moved up through layers?

I know the freeze/thaw cycle here can shift buried rocks upwards over time. Since the frost level is six feet, presumably it can move rocks that deep down. So can they tell if something has been shifted upwards in this way?

How would they deal with this?

[Reverend Blair]

Er...kind of a related question.

How do they tell if a fossil has moved up through layers?

I know the freeze/thaw cycle here can shift buried rocks upwards over time. Since the frost level is six feet, presumably it can move rocks that deep down. So can they tell if something has been shifted upwards in this way?

How would they deal with this?

Well, I'd deal with it by using heavy equipment and hydraulics. Maybe some home-made anfo if it was really stubborn.

You can kind of see what's happened there though. There's a pattern to the rocks that makes the shift apparent.

I live in a place with deep soil and rocks that are separated from one another. Patterns like that aren't apparent here, at least to me. Now, I know the scientists manage to date things anyway...everything from dinosaur fossils to recent native artifacts have been dated with accuracy...I just don't understand how.

[Gawdzilla Sama]

Well, I'd deal with it by using heavy equipment and hydraulics. Maybe some home-made anfo if it was really stubborn.

You can kind of see what's happened there though. There's a pattern to the rocks that makes the shift apparent.

I live in a place with deep soil and rocks that are separated from one another. Patterns like that aren't apparent here, at least to me. Now, I know the scientists manage to date things anyway...everything from dinosaur fossils to recent native artifacts have been dated with accuracy...I just don't understand how.

There's some awesome geology around here (southwest of St. Loser). When the weather improves Ayaan and I will get some shots to post.

Speaking of this, anybody recommend a good field geology primer for an non-science person?

[Reverend Blair]

I have to drive a couple of hours east or north to see awesome geology. A prairie boy like me can be pretty amazed by the Canadian Shield though.

Most of the fossil and artifact finds around here either come out of a river bank after the spring flood or get discovered when constructions workers or farmers are digging holes.

[Gawdzilla Sama]

I have to drive a couple of hours east or north to see awesome geology. A prairie boy like me can be pretty amazed by the Canadian Shield though.

Most of the fossil and artifact finds around here either come out of a river bank after the spring flood or get discovered when constructions workers or farmers are digging holes.

This lot is just a few miles from my house. The first pics are of a "recent" cut, 10 years old. The later ones are 70-80 years of exposure.

http://s691.photobucket.com/albums/vv27 ... a/Rocks01/

[Reverend Blair]

Very cool. It reminds me a lot of the way riverbanks look here as the water cuts into the clay...the definition of the layers and so on. Nothing has been compressed into rock here yet though.

It's pretty odd when you see the prairies turn into Canadian shield here. It happens pretty quickly, like the glaciers just kind of ran out of dirt to drop or something. I should likely start a photobucket account and get some of the images on-line. Of course then I'd have to scan a bunch of Kodachromes to put them up too.