To: All Msg #291, Nov1793 12:21AM Subject: Re: Teaching C'ism? (Was: Re: Churches as Leech

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From: Chris Nedin To: All Msg #291, Nov-17-93 12:21AM Subject: Re: Teaching C'ism? (Was: Re: Churches as Leeches) Organization: Geology & Geophysics, Adelaide University From: cnedin@geology.adelaide.edu.au (Chris Nedin) Message-ID: Followup-To: talk.origins Newsgroups: alt.atheism,talk.origins In article , smullins@cidmac.ecn.purdue.edu (Scott H Mullins) wrote: > > In article <2buaa8$soc@gazette.bcm.tmc.edu> gwinward@bcm.tmc.edu (Georgia L. > Winward) writes: > >The Grand Canyon was formed by some great body of > >water, so why not the great flood? > > There is strong evidence of catastrophic flooding in eastern > Washington state and Oregon. If this is supposedly what caused > the Grand Canyon then why don't we see the same type of evidence > in Arizona that we see in Washington? Do you know what the > relationship is between the rate of erosion, the hardness of the > material being eroded, and the slope of resulting formation? > I think geologists do. > > Chris Nedin, would you please comment on this for our edification > and to correct any (stupid) mistakes I might have made? No, there are no mistakes. I answered this yesterday, but was in a bit of a rush, so I will answer it again. Weathering-limited slopes are directly dependent on the relative resistance of the parent rock. There is a high correlation between rock mass strenth and the angle developed on the slope: 100-| | 90-| * | * 80-| * Rock | * Mass 70-| * Strength | * 60-| * | * 50-| | 40-| | = 0_|_____________________________ | | | | | | | | | | 10 20 30 40 50 60 70 80 90 100 Angle of slope Thus the higher the rock mass strength, the steeper the slope. Solid rock, provided it isn't jointed or fractured, has a high mass strength and a high cohesiveness factor (since the particles are bonded or cemented together) and so will produce a steep slope, even up to and beyond (overhang) 90 degrees. This situation can not occur in unconsolidated sediments, which have a low mass strenth and a low cohesive factor (because the particles are unconsolidated) thus slopes produced in low cohesive sands will stand at an angle of repose which is approximately 35 degrees. Higher angles are possible but the slope will be unstable and the slope will soon revert to the lower angle by slumping. Thus if the Grand Canyon was cut in a single event, just after the Flood, the sediment must have been unconsolidated and thus would not support a slope any greater than 35 degrees. The fact that the vast majority of slopes within the Grand Canyon are much steeper than this, indicates that the original material was consolidated, or lithified, into rock before the canyon was cut. Chris -------------------------------------------------------------------- | cnedin@geology.adelaide.edu.au | "How can Nedin be trusted" | | Dept. of Geology & Geophysics | C Wieland Director, | | University of Adelaide | Creation Research Foundation, | | South Australia 5005 | Queensland Australia | --------------------------------------------------------------------

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