----- Original Message -----
From: Charles Carrigan
To: Allen Roy ; American Scientific Affiliation
Sent: Wednesday, August 22, 2001 1:58 PM
Subject: Re: Response to Why YEC posting
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,
Chuck
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Charles W. Carrigan
Univ. of Michigan - Department of Geological Sciences
2534 C.C. Little Bldg.
425 E. University Ave.
Ann Arbor, MI 48109-1063
cwcarrig@umich.edu
http://www-personal.umich.edu/~cwcarrig/
"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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