Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9164 total)
3 online now:
Newest Member: ChatGPT
Post Volume: Total: 916,913 Year: 4,170/9,624 Month: 1,041/974 Week: 368/286 Day: 11/13 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   YECs, how do you explain meandering canyons?
edge
Member (Idle past 1736 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 16 of 43 (169816)
12-18-2004 10:55 PM
Reply to: Message 15 by TheLiteralist
12-18-2004 10:13 PM


Re: A simple answer.
Walt Brown: "Release of Grand Lake’s vast waters first eroded hundreds of meters of relatively soft Mesozoic sediments off northern Arizona. Once surface erosion was completed, downcutting through the harder Kaibab limestone began."
Nonsense. There is no evidence for this except that the Mz rocks happen to not be present at the GC. However, if there were such erosion of the Mz rocks, there should be some kind of channeling and sheet runoff features all over the Kaibab Uplift. There aren't.
Walt: "As erosion cut deeper beneath the water table, more water, under greater pressure, was released from the water-saturated sediments flanking the canyon."
Fortunately, for us, Walt does not practice hydrogeology. Ground water cannot be regionally under excessive pressure when exposed to surface waters. Also, he has no idea what releasing such pressure would do or the evidence it would leave. This only makes the cliffs of the GC MORE unlikely.
Walt: "This escaping water cut dozens of side canyons entering the Grand Canyonlarge canyons previously unexplained because they have no significant surface flow entering them. Subsurface flow and landslides were extreme."
There is no evidence of such jetting of water from the canyon walls. The side canyons form normal dendritic patterns, sometimes controled by preexisting brittle-rock structue. I'm not sure what he means by 'subsurface flow', but extreme landslides may be actually correct. We know that this is the modern method of forming the canyon and probably the side canyons: landslide dams and breeching of dams.
Walt: "The weight of material removed from northern Arizona produced isostatic uplifts that account for the uplift of the Kaibab Plateau. This produced much faulting and volcanism, the barbed canyons, and layered strata that dip down and away from Marble Canyon and Grand Canyon."
It is true that erosion results in isostatic uplift. However, I would love to see Walt's actual calculations on this.
L: Actually, it is not even MY knowledge of the subject; it is Walt Brown's...I know pretty much nothing about geology.
Well, then, you have something in common with Walt...

This message is a reply to:
 Message 15 by TheLiteralist, posted 12-18-2004 10:13 PM TheLiteralist has replied

Replies to this message:
 Message 20 by TheLiteralist, posted 12-20-2004 9:14 AM edge has replied

  
edge
Member (Idle past 1736 days)
Posts: 4696
From: Colorado, USA
Joined: 01-09-2002


Message 26 of 43 (172209)
12-30-2004 12:37 AM
Reply to: Message 20 by TheLiteralist
12-20-2004 9:14 AM


Re: Walt Brown's Grand Canyon Stuff
quote:
If I understand Walt Brown correctly, he is attempting to explain the barbed canyons, of course, which apparently run in the OPPOSITE direction of the flow of the Colorado river.
Perhaps you could give us an example of such 'barbed canyons'. I don't suppose you or Walt would consider that such canyons are controlled by rock structure formed in competent rocks? Nah, that would make too much sense since we see it everywhere else in the world...
quote:
Your last two sentences (in the quote above) seem to offer SOME support to his ideas. Is it possible for his overall Grand Canyon theory to have merit while some details are incorrect?
In this case, no. There is no evidence of the break out of a large flood-stranded lake. We know that thousands, if not millions of small dams have formed in the GC and this may have contributed to the erosion of hard rocks.
quote:
I think his reference to "subsurface flow" is an attempt to describe water from the water table running into the canyons formed by the breached dam (probably not two completely separate and independant events).
There is no need to explain this.
quote:
My Understanding of Walt Brown's Canyon Formation Scenario
If I'm getting the picture in my mind correct, the land has a slight tilt counter to the flow of the river (above the river, apparently). So, I *think* that Walt Brown is proposing the dam broke and Grand Lake emptied. The backwards tilt of the land wasn't enough to overcome the general flow of the water from the breached dam.
In the scenario you are talking about, the 'tilt of the land' has nothing to do with it. There is no evidence of a dam breach to form the GC.
quote:
The Grand Lake waters made their own canyon system flowing away from Grand Lake, but this canyon system cut beneath the water table. The water in the water table (influenced by the backwards tilt of the land) made the canyons that run in the opposite direction of the Colorado River flow. Of course, this whole scenario would probably make a different water table level; so it could happen only once.
Or never... I can make no sense of your story. Basically, Walt has no clue about erosion or erosional processes.
quote:
About the Meanders
(This is addressed really to everybody, not just Edge.)
Now, here I go out on a limb. How much merit would there be to the idea of (assuming a breached dam scenario) the breached dam waters creating meanders due to the backwards tilt of the land?
You are going out on a limb for Walt? Sorry, but this makes no sense at all: completely different flow regimes. By the way just where is your dam?
quote:
Seems that the proposed Grand Lake waters would have a general downhill flow (due to it being a breached dam), but the backwards tilt might have been a somewhat countering force to the general flow of the Grand Lake waters.
The backward tilt has nothing to do with it. On the downstream side, the tilt is in the direction of flow.
quote:
{Added by edit}
I find the idea that the Flood laid down the sediments in the rising stages and then cut the canyon in the receding stages a bit unrealistic. The idea about the cliffs not being able to support themselves at this stage pretty much refutes such reasoning. That's why I keep emphasizing that many creationists do not take this view.
You are being too reasonable to be a YEC.

This message is a reply to:
 Message 20 by TheLiteralist, posted 12-20-2004 9:14 AM TheLiteralist has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024