Re: Response to Why YEC posting

From: Charles Carrigan (
Date: Wed Aug 22 2001 - 16:58:08 EDT

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    At 12:01 PM 8/22/01 -0700, you wrote:

    Cases in point.
    1:  I know you are aware of the Uinkaret Plateu lava flows which flowed down
    into Grand Canyon.  These have been dated by a Pb-Pb isochron age in the
    neighborhood of 2.6 billion years and by a Rb-Sr isochron date somewhere
    around 1.34 billion years.  Everyone rejects these computed ages because it
    is obvious that the lava cannot be that old.  They must be younger than
    Grand Canyon which is variously dated between 1 and 5 million years.   An
    assortment of reasons concerning the "original abundances of isotopes" have
    been proposed to try to explain the discrepancy, but the most important
    point is that the dates are rejected because it is "known" that the lava
    cannot be that old.   The rocks are assumed to be young therefore computed
    dates which indicate vast ages are rejected.

    2:  Also in Grand Canyon are the Cardenas Basalts which are dated by a Rb-Sr
    isochron near 1.07 billion years. Because the Cardenas Basalts are among the
    oldest exposed rocks in Grand Canyon everyone assumes that the Cardenas
    Basalt's are old enough for the computed dates to be accepted as valid.

    Can you provide references for these dates please? 

    Thank You,

    Charles W. Carrigan
    Univ. of Michigan - Department of Geological Sciences
    2534 C.C. Little Bldg.
    425 E. University Ave.
    Ann Arbor, MI  48109-1063

    "People think in five generations -- two ahead, two behind -- with heavy concentration on the one in the middle.  Possibly that is tragic, and possibly there is no choice.  The human mind may not have evolved enough to be able to comprehend deep time.  It may only be able to measure it."
                                                                       - John McPhee, Basin and Range

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