Richard Dawkins disappoints again

[The Barbarian]

You said it more succinctly and clearly than anyone else has done. Hopefully, that will be sufficient.

 

[dcalling]

Looks like uplift, although younger; it's not nearly as deep as other cases. If it is uplift, it's likely not the uplift of an ancient river as was the case of the Grand Canyon; meanders are not extreme, as you see in very old rivers.

I was primarily talking about image 2, which I will post again. You can see the rock layers match on all sides, meaning it is definitely not uplift.

 

[The Barbarian]

I think you misunderstand what "uplift" means. It means the entire plateau was raised upwards. This increased the difference between the river upstream from the outlet.

And that made it run faster, like a new river. The process is called "rejuvenation." And when that happens, the river can't meander, but merely erodes downward into the existing bed, which gets deeper and deeper as the river cuts into the underlying rock. The layers you see in the canyon were laid down long before the river cut into them.

 

[dcalling]

I think you misunderstand what "uplift" means. It means the entire plateau was raised upwards. This increased the difference between the river upstream from the outlet.

And that made it run faster, like a new river. The process is called "rejuvenation." And when that happens, the river can't meander, but merely erodes downward into the existing bed, which gets deeper and deeper as the river cuts into the underlying rock. The layers you see in the canyon were laid down long before the river cut into them.

OK let's get it clear.

We all agree on:
1. The layers in the canyon were laid down long before river cut into them
2. water has more energy potential when its higher.

What we don't agree on:
How did the meander in the canyon form? Kom think it is uplift and incision (or initially he think it is cemented sediment, not sure which version he is on). How about you? If it is eroding, how did the inital path way form?

 

[Job 33:6]

It is uplift and incision of the cemented sediment. ∆ but the uplift didn't form the shape of the meanders, the shape of the meanders are the product of a historical river. The depth of the meanders is a product of uplift and the current river cutting down through the rock.

 

[dcalling]

It is uplift and incision of the cemented sediment. ∆ but the uplift didn't form the shape of the meanders, the shape of the meanders are the product of a historical river. The depth of the meanders is a product of uplift and the current river cutting down through the rock.

Here is your assumption:
1. at very ancient times, a river was on soft ground and formed meander.
2. it formed into a shallow meander (shallow compare to the current depth)
3. later something happened and the whole plane turned into rock (cemented)
4. after that another river keep cutting on this rock on the original meander and keep cutting deeper and deeper

Here are the questions on that assumption:
1. On step 3, how did the entire place turned into rock? have we ever observed such cementing?
2. On step 4, during the "cutting" process, since the rocks are not disovlable (unlike some other place where the limes can be slowly disoved), it will take literaly millions or billions of years to cut. But since there are fault lines around, it will be much easier for the fault lines to change how water flow, i.e. can you imagine nature let this water slowly peaceful cut away the rock without been interrupted?

To me, it seems other suggestions are much more credible, I have read people suggesting ice movements, or combined earth quake, ice cover etc, could also be under ground weak spots that induced faults and during earth quake they split like that due to weakness, and later combined with very strong mealting ice water smoothing the surface.

 

[Job 33:6]

Your first #1 is correct. The number 2 is also correct. These would have occurred in the cenozoic.

In number 3 you said "something happened and the whole plane turned into rock". No no, the mesozoic rocks that are now exposed, already existed. They predated the river as we have discussed before. Point bars, soft sediments of recent age (cenzoic age) are no longer present in this area. The exposed rocks are mesozoic, some 200 million years old, whereas the stream is far younger, perhaps less than 10 million years old of the cenozoic.

Then uplift occurred and water cut down into mesozoic and paleozoic rock, cenozoic rock including the soft sediment is no longer present.

Geologic time scale - Wikipedia
https://pbs.twimg.com/media/DK6toctVwAUNdTY.jpg



1. The rocks that are visible, pre exist the current river, as we have already discussed. Much of the exposed rock in the images we are looking at is mesozoic. Young rocks and cenozoic deposition in many parts of the canyon have been washed away. The ancient point bars of the cenozoic area gone and eroded away, though as discussed, even older point bars and lenticular stream deposits are present in Mesozoic rock as well.

Have we observed cementing? Yes of course.
GEOL 4500 - Sedimentary Geology

Cores present us with sediment and rocks at great depth, but also chemistry and physics based studies allow us to test how sediment functions under pressure and heat. We can also observe things like subduction with geophysical surveying equipment. There are a number of ways compaction and cementation can occur.

In some cases, faults have manipulated the direction of the colorado (https://pbs.twimg.com/media/DK6toctVwAUNdTY.jpg), however major faults are not present all throughout the stream. The image with the meanders for example, does not depict any major faults. So, no major faults are affecting that section.

And as it has been said before, earthquakes do not form meanders. Ice and glaciers also do not meander. So im not sure why you think those alternatives better explain the formation of meanders.


It's quite the transition going from a young earthers 6000 year old view, to a view that encompasses 4.5 billion years. I recommend reviewing the geologic timescale to understand what is being discussed. There is evidence for many many many events that have occurred in the grand canyon and if you don't have a grasp on the geologic timescale , you will have trouble understanding the order in which these events have occurred.

 

[Job 33:6]

See this image. In red are areas where faults have manipulated the direction of the river. However in green, you dont really have major faults cross cutting the meanders. Its a combination of both manipulation, as well as peaceful erosion. Also notice how the faults are all parallel to one another. This is because compressional faulting occurred in a single direction, as did extensional faulting as a product of tectonic motion. Also notice how some of the faults splinter into pieces. This propogation faulting does not occur in soft sediments. Kaibab limestone is also permian in age. 250-290 million years old.

 

[dcalling]

Your first #1 is correct. The number 2 is also correct. These would have occurred in the cenozoic.

In number 3 you said "something happened and the whole plane turned into rock". No no, the mesozoic rocks that are now exposed, already existed. They predated the river as we have discussed before. Point bars, soft sediments of recent age (cenzoic age) are no longer present in this area. The exposed rocks are mesozoic, some 200 million years old, whereas the stream is far younger, perhaps less than 10 million years old of the cenozoic.

This is the part I want to know your position on. the mesozoic rocks, when exposed, what shape are they? Are they already have the "S" shape or flat?

i.e. I am going to assume that ancient water meanders on soft cediments of some recent age x million years ago, washed most of it away, now it touches on mesozoic rocks, does it keep eroding on the mesozoic rocks?

Then uplift occurred and water cut down into mesozoic and paleozoic rock, cenozoic rock including the soft sediment is no longer present.

Geologic time scale - Wikipedia
https://pbs.twimg.com/media/DK6toctVwAUNdTY.jpg



1. The rocks that are visible, pre exist the current river, as we have already discussed. Much of the exposed rock in the images we are looking at is mesozoic. Young rocks and cenozoic deposition in many parts of the canyon have been washed away. The ancient point bars of the cenozoic area gone and eroded away, though as discussed, even older point bars and lenticular stream deposits are present in Mesozoic rock as well.

Have we observed cementing? Yes of course.
GEOL 4500 - Sedimentary Geology

Notice how they use the word "may". They are not sure. How did the entire plane cemented into rock? Where did all the material that needed to crystalize come from? Don't you think it is much likely those are the cooled mental of the earth that got pushed up?

Cores present us with sediment and rocks at great depth, but also chemistry and physics based studies allow us to test how sediment functions under pressure and heat. We can also observe things like subduction with geophysical surveying equipment. There are a number of ways compaction and cementation can occur.

In some cases, faults have manipulated the direction of the colorado (https://pbs.twimg.com/media/DK6toctVwAUNdTY.jpg), however major faults are not present all throughout the stream. The image with the meanders for example, does not depict any major faults. So, no major faults are affecting that section.

And as it has been said before, earthquakes do not form meanders. Ice and glaciers also do not meander. So im not sure why you think those alternatives better explain the formation of meanders.


It's quite the transition going from a young earthers 6000 year old view, to a view that encompasses 4.5 billion years. I recommend reviewing the geologic timescale to understand what is being discussed. There is evidence for many many many events that have occurred in the grand canyon and if you don't have a grasp on the geologic timescale , you will have trouble understanding the order in which these events have occurred.

Not sure where you got the idea that I think the earth is 6000 year old. The part I disagree with you on is how the meander is formed, which got too many unanswered questions.

But do have a question, how do you tell "Kaibab limestone is also permian in age. 250-290 million years old"?

 

[Job 33:6]

The river would continue to erode through rocks directly below it, until it reached an equilibrium with the underlying groundwater. Which means that, after eroding upperlying sediment (where it had taken shape and meandered) and other cenozoic and upperlying rock, once it reached the mesozoic layers, it would have simply kept eroding in the shape of itself that it had taken at a prior time.

Just as when erosion continued beyond mesozoic layers into paleozoic layers, it maintains its shape because the mesozoic layers guide it into the paleozoic layers.

In some cases, where there is a fault, as you noted, the river might change its shape to some extent. But where there are undisturbed, laterally continuous layers, the river stays as it is.

Also, it should be noted that it is not the river that laterally erodes layers for hundreds of miles. Lateral continuity and original horizontality are just features of pre existing rock. Gravity and erosional forces of wind, water and ice, draw landforms to be laterally continious and horizontal.

To understand how rock layers are dated, i would recommend learning about relative dating methods. Understanding things like superposition, cross cutting relations, inclusions, original horizontality, faunal succession and lateral continuity. Once these are understood, then we could begin talking about the ages of layers.

Relative dating - Wikipedia

 

[dcalling]

The river would continue to erode through rocks directly below it, until it reached an equilibrium with the underlying groundwater. Which means that, after eroding upperlying sediment (where it had taken shape and meandered) and other cenozoic and upperlying rock, once it reached the mesozoic layers, it would have simply kept eroding in the shape of itself that it had taken at a prior time.

Just as when erosion continued beyond mesozoic layers into paleozoic layers, it maintains its shape because the mesozoic layers guide it into the paleozoic layers.

In some cases, where there is a fault, as you noted, the river might change its shape to some extent. But where there are undisturbed, laterally continuous layers, the river stays as it is.

Also, it should be noted that it is not the river that laterally erodes layers for hundreds of miles. Lateral continuity and original horizontality are just features of pre existing rock. Gravity and erosional forces of wind, water and ice, draw landforms to be laterally continious and horizontal.

To understand how rock layers are dated, i would recommend learning about relative dating methods. Understanding things like superposition, cross cutting relations, inclusions, original horizontality, faunal succession and lateral continuity. Once these are understood, then we could begin talking about the ages of layers.

Relative dating - Wikipedia

So you think what happened is water eroded on softer material, meandered, and just keep on eroding deeper and deeper down to the bottom rocks?

There are multiple issues with your assumption. First, don't you think it will be much easier for water to keep moving the meander around then to eroding down to harder rocks (i.e. they are likely to slid the meander on top of rocks).

Second, just curious, do you think both meander below are formed by billions of years of eroding?

 

[The Barbarian]

So you think what happened is water eroded on softer material, meandered, and just keep on eroding deeper and deeper down to the bottom rocks?

Yep. When a river speeds up, it no longer meanders, but digs deeper into the existing channel. This is why young rivers don't meander; they move too fast. Eventually, water erodes down into rock.

There are multiple issues with your assumption. First, don't you think it will be much easier for water to keep moving the meander around then to eroding down to harder rocks (i.e. they are likely to slid the meander on top of rocks).

Nope. Demonstrably wrong. Young rivers observably don't meander, and they cut down into rock.

Second, just curious, do you think both meander below are formed by billions of years of eroding?

Millions anyway.

 

[dcalling]

Nope. Demonstrably wrong. Young rivers observably don't meander, and they cut down into rock.

Why young rivers don't meander? As long as the conditions met any river will meander right?
Also if young river does not meander, and cut into rocks, then the river will be a straight river in the rock, and rocks does not meander since you can't "grow" rock, that is why @KomatiiteBIF always points to an ancient river on not-yet-cemented soil.

Anyways, you do think that both images are formed by "millions" years of eroding? @KomatiiteBIF how about you?

 

[The Barbarian]

Why young rivers don't meander?

They move too fast, and sediment doesn't drop very well. So meanders can't form.

Young River - the upper course

The beginning of a river, when it flows quickly with lots of energy, is called a young river. The river here is smaller and usually has a rapid, tumbling flow that cuts a narrow channel through rocky hills or mountains.

As long as the conditions met any river will meander right?

Older, slow-moving rivers will meander, because they drop sediment constantly on the inside banks of curves, and slowly erode out the outside banks.

Also if young river does not meander, and cut into rocks, then the river will be a straight river in the rock

It will still turn here and there, as it seeks the lowest level. It will follow the contours of the surface. It just won't move the bed of the river around. Instead, it cuts deeper and deeper into the rock.

and rocks does not meander since you can't "grow" rock,

Hence, the v-shaped valleys of young rivers, as opposed to the wide valleys of older rivers.

And since we can measure how much a river cuts into rock, yes those are millions of years of erosion. Why not a huge flow of water? Because a huge flow would have erased those entrenched meanders. We have examples of sudden catatstrophic flows such as the Scablands in Washington, where an ice dam collapsed during the last ice age. They look nothing like the Grand Canyon.

 

[dcalling]

They move too fast, and sediment doesn't drop very well. So meanders can't form.

Young River - the upper course

The beginning of a river, when it flows quickly with lots of energy, is called a young river. The river here is smaller and usually has a rapid, tumbling flow that cuts a narrow channel through rocky hills or mountains.



Older, slow-moving rivers will meander, because they drop sediment constantly on the inside banks of curves, and slowly erode out the outside banks.



It will still turn here and there, as it seeks the lowest level. It will follow the contours of the surface. It just won't move the bed of the river around. Instead, it cuts deeper and deeper into the rock.

The turning here and there is due to the shape of the rocks and not meandering.

Hence, the v-shaped valleys of young rivers, as opposed to the wide valleys of older rivers.

And since we can measure how much a river cuts into rock, yes those are millions of years of erosion. Why not a huge flow of water? Because a huge flow would have erased those entrenched meanders. We have examples of sudden catatstrophic flows such as the Scablands in Washington, where an ice dam collapsed during the last ice age. They look nothing like the Grand Canyon.

Excatly, the second image I showed is Scablands . Now with that in mind, does the second image (shown below) look like caused by "sudden catastrophic flows"?

 

[Job 33:6]

They move too fast, and sediment doesn't drop very well. So meanders can't form.

Young River - the upper course

The beginning of a river, when it flows quickly with lots of energy, is called a young river. The river here is smaller and usually has a rapid, tumbling flow that cuts a narrow channel through rocky hills or mountains.



Older, slow-moving rivers will meander, because they drop sediment constantly on the inside banks of curves, and slowly erode out the outside banks.



It will still turn here and there, as it seeks the lowest level. It will follow the contours of the surface. It just won't move the bed of the river around. Instead, it cuts deeper and deeper into the rock.



Hence, the v-shaped valleys of young rivers, as opposed to the wide valleys of older rivers.

And since we can measure how much a river cuts into rock, yes those are millions of years of erosion. Why not a huge flow of water? Because a huge flow would have erased those entrenched meanders. We have examples of sudden catatstrophic flows such as the Scablands in Washington, where an ice dam collapsed during the last ice age. They look nothing like the Grand Canyon.

That's another concept to be recognized. The shape that a river forms when it flows. @dcalling understand the V shape that rivers form as they erode land. As opposed to a U shape formed by glaciers.

 

[Job 33:6]

Also, not only is the river flowing faster, it looses its equilibrium with the water table when uplifted.

So it actually becomes easier for the river to flow downward, rather than side to side against underlying rock layers as is descends toward the water table. @dcalling

It's just the way physics works.

 

[The Barbarian]

Excatly, the second image I showed is Scablands . Now with that in mind, does the second image (shown below) look like caused by "sudden catastrophic flows"?

The river was there long before the scablands formed. They happened in maybe a few weeks when the ice dam drained Lake Missoula. You're confusing the scablands with the geology that went on before.

The flood itself did produce erosion, of course, but it was like this:

 

[The Barbarian]

Here's a higher view of your river:

The river, having gradually cut down through the rock is ancient. The channeled scablands around it are recent, from the last ice age.

The river follows a fairly straight course because of conditions that existed before the catastrophic flooding.

Meanders such as we see in the Colorado river:

Would have been broken through by the flood, carrying huge boulders along its path.

 

[dcalling]

Here's a higher view of your river:

The river, having gradually cut down through the rock is ancient. The channeled scablands around it are recent, from the last ice age.

The river follows a fairly straight course because of conditions that existed before the catastrophic flooding.

Meanders such as we see in the Colorado river:

Would have been broken through by the flood, carrying huge boulders along its path.

it is always easy to argue on ancient river millions of years ago, older than the landscape. of course impossible to prove. How do you know it is millions, but not billions or 100 thousands?

How about this, is this from ancient waterfall or the river got cut?