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Author Topic:   Exploring the Grand Canyon, from the bottom up.
JB1740
Member (Idle past 3325 days)
Posts: 132
From: Washington, DC, US
Joined: 11-20-2007


Message 241 of 260 (438269)
12-03-2007 4:13 PM
Reply to: Message 240 by jar
11-29-2007 9:12 PM


Re: Now onward and upward.
Is that reasonable so far?

Yep, except:

First instead of the somewhat slow sea or shore line environment of the Nankoweap, there needed to be some pretty active volcanism to create the igneous rocks that get weathered to make the Chuar group.

This is probably true, but doesn't have to be (e.g., if there were preexisting igneous rocks in the Nankoweap or something, that could eliminate the need for active volcanism bewteen Nankoweap and Chuar time.

Does that also mean that the lower, larger material likely came from a closer, steeper source and as that source was weathered down, away and back from the point of deposition, we see small material that has been transported further and thus more weathered? Also if we were seeing something being worn down, would we see the slope decrease with weathering and so slower, lower energy transport?

More than likely yes.


This message is a reply to:
 Message 240 by jar, posted 11-29-2007 9:12 PM jar has responded

Replies to this message:
 Message 242 by jar, posted 12-03-2007 4:20 PM JB1740 has responded

    
jar
Member
Posts: 28667
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.6


Message 242 of 260 (438270)
12-03-2007 4:20 PM
Reply to: Message 241 by JB1740
12-03-2007 4:13 PM


Re: Now onward and upward.
This is probably true, but doesn't have to be (e.g., if there were preexisting igneous rocks in the Nankoweap or something, that could eliminate the need for active volcanism bewteen Nankoweap and Chuar time.

That makes sense.

What about the ash layers though? Is it common for a volcanic event to produce both ash and lava? Would each ash layer indicate a separate event? If so, I assume that there would be some time between such events to account for the intervening material?

Any chance you can help me over on Salt of the Earth (on salt domes and beds).


Aslan is not a Tame Lion
This message is a reply to:
 Message 241 by JB1740, posted 12-03-2007 4:13 PM JB1740 has responded

Replies to this message:
 Message 243 by JB1740, posted 12-03-2007 4:29 PM jar has responded

  
JB1740
Member (Idle past 3325 days)
Posts: 132
From: Washington, DC, US
Joined: 11-20-2007


Message 243 of 260 (438272)
12-03-2007 4:29 PM
Reply to: Message 242 by jar
12-03-2007 4:20 PM


Re: Now onward and upward.
What about the ash layers though? Is it common for a volcanic event to produce both ash and lava?

No, you're totally right. Volcanoes tend to do one or the other and those require active (duh...) volcanism. I was saying (poorly) that it is possible that you could have an older igneous source weathering to produce the sediment in the lower Chuar that might NOT be related to the activity producing the periodic ash layers. It is a more complicated explanation than necessary but nature does tell Occam to piss off on occasion. I wasn't talking about the ash layers right there but that probably wasn't clear.

Would each ash layer indicate a separate event?

Yes

If so, I assume that there would be some time between such events to account for the intervening material?

Yep...exactly. You're a quick study.

Any chance you can help me over on Thread Salt of the Earth (on salt domes and beds)

Hah...you caught me. I've been ignoring that one for the time being because whereas I know a bit about salt deposition, I don't remember all that much detail about salt domes and salt tectonics. I've got an old book that has some stuff on salt tectonics but I haven't been able to put my hand on it. So, the answer to your question is probably...but give me a bit to see what I remember/can find.


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 Message 242 by jar, posted 12-03-2007 4:20 PM jar has responded

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jar
Member
Posts: 28667
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.6


Message 244 of 260 (438275)
12-03-2007 4:49 PM
Reply to: Message 243 by JB1740
12-03-2007 4:29 PM


Next up-Sixty Mile Formation.
Great. I think I understand all this so far.

The last formation in the Super Group is the Sixty Mile Formation and after that we can get to some of the fun stuff I am dying to understand.

I have heard that the makeup of the Sixty Mile formation is somewhat similar to the Chuar group but that it contains more breccias and other conglomerates.

What more can you tell us?


Aslan is not a Tame Lion
This message is a reply to:
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RAZD
Member
Posts: 18256
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.2


Message 245 of 260 (568087)
07-04-2010 9:42 AM
Reply to: Message 244 by jar
12-03-2007 4:49 PM


Calling all geologists ... calling all geologists ...
Welcome back Jar,

This thread has been so wonderfully kept on track that it is a shame to let it slide.

The last formation in the Super Group is the Sixty Mile Formation and after that we can get to some of the fun stuff I am dying to understand.

I have heard that the makeup of the Sixty Mile formation is somewhat similar to the Chuar group but that it contains more breccias and other conglomerates.

What more can you tell us?

I believe a number of the geologists that have provided such valuable input on this topic are still around (perhaps hiding in the wings waiting for a good geology topic).

Can someone pick up the dialogue at this point?

Enjoy.


we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 244 by jar, posted 12-03-2007 4:49 PM jar has not yet responded

  
jar
Member
Posts: 28667
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.6


Message 246 of 260 (568098)
07-04-2010 10:13 AM


General message
Welcome to any new folk. Just a few points.

Before you jump in, please read through the thread. Yeah, I know that is a lot of messages but there is also a lot of information here.

We are going slow on purpose, step by step working our way up from the bottom of the Grand Canon.

So far we have just reached the Sixty Mile Formation in the Super group.

As mentioned in the OP...

quote:

I'd like for us to discuss the Grand Canyon, beginning with the lowest, oldest layers and then working up to the top, layer by layer. I'd like to see explanations for each layer, it's composition, the environment when it was created, and get questions about that layer answered before we move up to the next layer.


Anyone so limited that they can only spell a word one way is severely handicapped!
  
AdminAsgara
Administrator
Posts: 2072
From: The Universe
Joined: 10-11-2003


Message 247 of 260 (609815)
03-23-2011 11:26 AM


Bump
This was such an important and useful thread. I would really like to see it continue. If Jar can find a geologist to work off of (Maybe Rox will come back in and help)
Replies to this message:
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roxrkool
Member (Idle past 277 days)
Posts: 1493
From: Nevada
Joined: 03-23-2003


Message 248 of 260 (610050)
03-25-2011 8:51 PM
Reply to: Message 247 by AdminAsgara
03-23-2011 11:26 AM


Re: Bump
Oh I would love to!

It's just that when I was able to contribute before, I had access to a lot of literature and a lot more time -- writing these posts can be quite time-consuming -- and these days I'm pretty limited with both. I'll see what I can do. I really enjoyed it and also learned a lot. This is one of my favorite threads.

And I'm happy to see jar is back.


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jar
Member
Posts: 28667
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.6


Message 249 of 260 (610052)
03-25-2011 9:03 PM
Reply to: Message 248 by roxrkool
03-25-2011 8:51 PM


Re: Bump
Good to see you back and thanks rox. Sure need your help.

Here's where we are so far, just at the very bottom of the sixty-mile group. Any chance you can tell us about just the bottom layer of the sixty-mile group?


Anyone so limited that they can only spell a word one way is severely handicapped!
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RAZD
Member
Posts: 18256
From: the other end of the sidewalk
Joined: 03-14-2004
Member Rating: 3.2


Message 250 of 260 (633491)
09-14-2011 12:11 PM
Reply to: Message 249 by jar
03-25-2011 9:03 PM


Re: Bump for any new GEOLOGISTS to help out ...
This is a great thread, and I'd like to see some more progress from the bottom layers.

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click)

This message is a reply to:
 Message 249 by jar, posted 03-25-2011 9:03 PM jar has responded

Replies to this message:
 Message 251 by jar, posted 09-14-2011 12:22 PM RAZD has acknowledged this reply

  
jar
Member
Posts: 28667
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.6


(1)
Message 251 of 260 (633492)
09-14-2011 12:22 PM
Reply to: Message 250 by RAZD
09-14-2011 12:11 PM


Re: Bump for any new GEOLOGISTS to help out ...
And I'd love it if the new folk began at the beginning and climbed up with us.

Anyone so limited that they can only spell a word one way is severely handicapped!

This message is a reply to:
 Message 250 by RAZD, posted 09-14-2011 12:11 PM RAZD has acknowledged this reply

Replies to this message:
 Message 252 by Chuck77, posted 09-15-2011 2:33 AM jar has responded

  
Chuck77
Inactive Member


(1)
Message 252 of 260 (633612)
09-15-2011 2:33 AM
Reply to: Message 251 by jar
09-14-2011 12:22 PM


Re: Bump for any new GEOLOGISTS to help out ...
And I'd love it if the new folk began at the beginning and climbed up with us.

This seems cool. Are you guys starting over again or should I catch up?


This message is a reply to:
 Message 251 by jar, posted 09-14-2011 12:22 PM jar has responded

Replies to this message:
 Message 253 by jar, posted 09-15-2011 8:53 AM Chuck77 has responded

  
jar
Member
Posts: 28667
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.6


(2)
Message 253 of 260 (633639)
09-15-2011 8:53 AM
Reply to: Message 252 by Chuck77
09-15-2011 2:33 AM


Re: Bump for any new GEOLOGISTS to help out ...
All the material is still the same so if you could begin at the beginning and read through the posts on each layer it will help you. I know there is a lot of material there and that is why we are doing this slowly, one layer at a time.

Anyone so limited that they can only spell a word one way is severely handicapped!

This message is a reply to:
 Message 252 by Chuck77, posted 09-15-2011 2:33 AM Chuck77 has responded

Replies to this message:
 Message 254 by Chuck77, posted 09-17-2011 3:53 AM jar has responded

  
Chuck77
Inactive Member


Message 254 of 260 (633910)
09-17-2011 3:53 AM
Reply to: Message 253 by jar
09-15-2011 8:53 AM


Re: Bump for any new GEOLOGISTS to help out ...
I know there is a lot of material there and that is why we are doing this slowly, one layer at a time

Ok, I should be ready by Christmas. My brain hurts from reading this complicated thread but am interested in participating.

Can you and RAZD maybe find a few good posts that sum up the thread so far that would bring me up to speed? If not i'll just lurk for a while.


This message is a reply to:
 Message 253 by jar, posted 09-15-2011 8:53 AM jar has responded

Replies to this message:
 Message 255 by jar, posted 09-17-2011 8:33 AM Chuck77 has not yet responded
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jar
Member
Posts: 28667
From: Texas!!
Joined: 04-20-2004
Member Rating: 2.6


(1)
Message 255 of 260 (633932)
09-17-2011 8:33 AM
Reply to: Message 254 by Chuck77
09-17-2011 3:53 AM


Re: Bump for any new GEOLOGISTS to help out ...
The purpose of the thread is to avoid summing up the process.

Yes, this is a difficult thread and yes it is complicated, but it is also really, really important, particularly for you, to understand just what processes are involved in each one of the stages, each layer. Take your time and if possible, touch base with us as you climb up each layer. If you have questions feel free to ask, but remember, only one layer at a time and starting at the bottom.


Anyone so limited that they can only spell a word one way is severely handicapped!

This message is a reply to:
 Message 254 by Chuck77, posted 09-17-2011 3:53 AM Chuck77 has not yet responded

  
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