Since I have read through the rest of this thread, I know this post has been addressed, but some responses ignored a few key errors and replies to responses just danced around other errors that were pointed out.
paulrob said:
Every evolutionist will tell you the canyon walls are sedimentary rock, and no creationist disputes that.
The first thing you need to understand is that this has nothing to do with evolution at all, so you should not be using the word "evolutionist." In the context of this discussion, "geologist" would be apt.
The composition of the canyon is not all sedimentary rock, to be technical. The Vishnu Schist, for example, outcrops at the bottom of the currently exposed canyon, and that is metamorphic rock. Additionally, there are igneous intrusions throughout the sedimentary layers. But that's a relatively minor point here.
What the evolutionist cannot twll you is how the sedimentary layers were all laid down with minimal interlayer erosion - as long periods of time would require.
That's false. That statement does nothing but demonstrate that you have not studied the stratigraphy of the Grand Canyon (or at least not with any meaningful level of understanding of what you were looking at).
There are several examples of "interlayer erosion" which are features termed
unconformities in geology.
There are two types of unconformities relevant here that appear at the Grand Canyon: an angular unconformity (where tilted strata are eroded to almost horizontal overlain by strata with horizontal bedding) and disconformities (eroded surfaces between horizontal sedimentary strata--more "interlayer erosion" that you are looking for).
Here's a cross section of the Grand Canyon (not the best one I was looking for, but it'll do for now):
Unconformities in the Grand Canyon are also labelled by blue lines in
this diagram.
As you can see, the Tapeats overlies tilted strata that were eroded to a horizontal surface--
this requires a disruption in sedimentary accumulation and erosion (which is incompatible with the continuous deposition of the global flood senario proposed by YECists).
Also, as you can see, there are erosional boundaries between layers such as between the Temple Butte/Muav, represented by wavy lines in the diagram. Erosional boundaries are also evident when there are sinkholes in limestone (remnant karst topography) filled in by sediment.
This requires a disruption in sedimentary accumulation and erosion (which is incompatible with the continuous deposition of the global flood scenario proposed by YECists).
Therefore, the reason why geologists don't tell you about continuous deposition without hiatuses and erosion, is because there are numerous examples in the Grand Canyon's geology that indicate such episodes of erosion. Your objection is simply unfounded.
On the other hand, precipitating sand and lime over a several hundred year period would produce the effect we see today.
Limestone is precipitated out of solution, sandstone is deposited by several different methods (wind, rivers, oceans, etc.) rather than precipitated.
The notion of the deposition of these layers over 100 years is inconsistent with the YEC flood model in the first place (they like to claim 1 year). But it's still unreasonable because there are vastly different types of rocks present that form in vastly different environments, some examples form only within strict controls. Really, you're just proposing storytelling rather than addressing the evidence itself.
take a look at Mt. St. helens, a 1/40 scale model of the Grand Canyon, created in front of the worlds media in 14 days.
They are nothing alike (not to mention that the canyon there was produced by human activity). Using that analogy demonstrates only that you must lack a basic understanding of geology. You even did all but concede the failure of this analogy when you tried to answer notto's questions (e.g., you answered "mostly ash" to the composition of Mt. St. Helens but don't see why that makes it an incompatible example).
Mt. St. Helens (MSH) and the Grand Canyon (GC) differ in the following ways:
1. MSH area is composed of pyroclastic material, loose mud, and remants of the dome of the volcano. GC is composed of sandstones, shales, limestones, etc.
2. Related to #1 is that the formation of limestones, for example, differs, especially in rate, to ash being spread over an area by an eruption. The material and its formation at both locations are vastly different.
3. MSH area is composed of unconsolidated sediment. GC is composed of lithified sediment. Outwash from the Colorado River indicates that material from the GC was eroded from rock.
4. MSH area is simple. GC is complicated because there is (a) erosion between layers indicating hiatuses in accumulation of material, (b) evidence of intrusions of magma into the sedimentary rock, (c) layers tilted by tectonic activity, etc.
5. MSH canyon does not have sharp gooseneck meanders like GC:
6. MSH does not contain fossils of a variety of organisms. GC contains fossils of a variety of organisms over a long period of time.
7. MSH does not contain secondary features like (a) sedimentary structures (e.g., large scale cross bedding of the Coconino SS at GC) or (b) trace fossils of organisms walking around in layers that have sediments on top of them (sediment cannot be deposited there with creatures walking around).
The list goes on and on, including notto's, that indicate that your analogy does not demonstrate
anything about the GC. It's entirely irrlevant to the issue.