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Author | Topic: Exploring the Grand Canyon, from the bottom up. | |||||||||||||||||||||||||||||||||||||||
JB1740 Member (Idle past 6204 days) Posts: 132 From: Washington, DC, US Joined: |
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.
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jar Member (Idle past 99 days) Posts: 34140 From: Texas!! Joined: |
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
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JB1740 Member (Idle past 6204 days) Posts: 132 From: Washington, DC, US Joined: |
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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jar Member (Idle past 99 days) Posts: 34140 From: Texas!! Joined: |
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
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RAZD Member (Idle past 1665 days) Posts: 20714 From: the other end of the sidewalk Joined: |
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. 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) • • •
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jar Member (Idle past 99 days) Posts: 34140 From: Texas!! Joined: |
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: Anyone so limited that they can only spell a word one way is severely handicapped! |
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AdminAsgara Administrator (Idle past 2562 days) Posts: 2073 From: The Universe Joined: |
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)
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roxrkool Member (Idle past 1248 days) Posts: 1497 From: Nevada Joined: |
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 (Idle past 99 days) Posts: 34140 From: Texas!! Joined: |
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 (Idle past 1665 days) Posts: 20714 From: the other end of the sidewalk Joined: |
This is a great thread, and I'd like to see some more progress from the bottom layers.
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)
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jar Member (Idle past 99 days) Posts: 34140 From: Texas!! Joined:
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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!
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Chuck77 Inactive Member
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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?
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jar Member (Idle past 99 days) Posts: 34140 From: Texas!! Joined:
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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!
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Chuck77 Inactive Member |
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.
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jar Member (Idle past 99 days) Posts: 34140 From: Texas!! Joined:
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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!
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