ISOCHRONS AND EVOLUTIONARY DATING  by Dr. Steven Austin

As the media constantly tells us,  the Grand Canyon is supposed to
be  "Exhibit A" proving evolution.   But have those  Grand  Canyon 
rocks  really  been proved to be billions of years  old?   Is  the 
media  giving  us the correct story?   I wrote  the  paper  "Grand 
Canyon Lava Flows: A Survey of Isotopic Dating Methods" (Institute 
for  Creation Research Impact No.  178,  April 1988) to  summarize 
some  of  my recent work on potassium-argon (K-Ar)  and  rubidium-
strontium (Rb-Sr) dating of Grand Canyon rocks.

The Rb-Sr isochron date of 1.1 billion years for the deeply buried 
Cardenas  Lavas (Precambrian) has been considered by  evolutionary 
geologists  to  be the "most secure" isotopic date  yet  made  for 
Grand Canyon strata. 

Several geologists have asked me if such  a  well
documented  date can be questioned.  They observe  that  the 
isochron method appears to internally validate the assumptions  of 
the dating method which creationists have criticised.   They  even 
note that the Rb-Sr isochron of 1.1 billion years for the Cardenas 
Lavas  overturned five K-Ar dates which gave a younger  age  (K-Ar 
Lavas before the Rb-Sr isochron was generated).

I  decided two years ago to generate my own "isochron dates"  from 
published  isotopic ratios and elemental analyses.   My  computers 
are  able to do the data manipulation to plot isochrons.   I  have 
started  the project by working on Grand Canyon lava  flows.   The 
Western Grand Canyon lava flows (Pleistocene) flowed over the  rim 
of  the Grand Canyon and blocked the Colorado River.   These  lava 
flows  lie  on the surface and look as fresh  as  recent  Hawaiian 
flows. 

  These Western Grand Canyon flows yielded a good "isochron 
date" of 1.5 billion years,  making them among the "oldest" strata 
yet  dated  in the Grand Canyon.   This isochron is  shown  in  my 
recent article (ICR Impact No. 178, April 1988).

Other  geologists and I have referred to these erroneous dates  as 
"fictitious isochrons."  These,  I believe,  cast severe doubts on 
some of the "accepted" isochron dates.   Fictitious isochrons need 
to be recognized and discussed.

The subject of radiometric dating can become very theoretical  and 
may get to be a "can of worms" in a hurry.   However,  I do invite 
your  comments  on my short article and want  to  discuss  various 
methods of dating Grand Canyon rocks.   I recommend that we  start 
by keeping the discussion on real rocks from the Grand Canyon  and 
limit our discussion to the popular methods used by the media  and 
geologists to date Grand Canyon rocks.  But please--no philosophy, 
religious arguments,  theoretical models, cosmological speculation 
or polemics!  I'm only interested in the facts.