Re: Where is Geology 401?

Glenn Morton (
Tue, 21 Apr 1998 21:42:05 -0500

Hi Norm,

I wish Steve Schimmerich or Steve Smith would jump in here as they are more
field geologists than this geophysicist, but I will express what I know about.
At 09:57 PM 4/21/98 -0400, Norm Smith wrote:
I have over the past few
>years scanned through every book on the subject that
>I have been able to find in the library at the
>Colorado School of Mines (which I suppose is a
>decent geology library). I have read those that
>seemed relevant to my question.

I would hope that CSM has a good geological library, I have hired people
from that institution to work for me. :-) They seemed to know what they are

>I do have before me your article in CRSQ June 1984.
>I'll mention in a moment some of the questions it
>leaves unanswered for me.

>Glenn wrote:
>>In other words, you are expecting a statistics book.
>>Why should geology, which settled on its foundations
>>a century ago, have to repeat this because Christians
>>won't go on field trips to actually look at the rocks.
>>Have you ever been on a geologic field trip over a
>>large subregional area?
>I would expect that a "foundations" type of book would
>have a strong statistical flavor because of the
>nature of the subject. Also, I don't see what the
>foundations being settled a hundred years ago has to
>do with the need for such a text.

Part of the problem that you want answered is answered by grad students
walking along outcrops and following the beds over long distances. If I can
look at the outcrop here, and then see the same rock in the same order half
a mile away, lying on top of the same rock type, I don't need statistics to
know that that is the same rock. and if you go over an arch, you can follow
one bed over the arch and then as the strata dip again into the earth, you
can find the same beds, in the same order, re-appearing in outcrop again.

I have a
>hard time believing that a graduate geology
>student can get away with not having a
>course that thoroughly examines those
>foundations. I find it simply amazing that some
>academic has not written a thorough quantitative
>analysis of correlation reliability.

Why? They can follow the major beds for long distances by means of walking
and those they can't then they use items like lithology, fossils and the
order once again. In the subsurface where we deal with geophysical logs, we
can find the same physical traits repeating in the same pattern in wells
from South Texas to Louisiana. But we can't find a way to mathematically
correlate the beds. Here is why. Starting at the yegua formation of South
Texas, it is a sandy interval with some lignite and pebbles at the base,
below this is the Cook Mountaint which has a shale, a sand a glauconitic
sand and lignitic clays in descending order. Below this is the Sparta which
is largely a shale overlying a sand, beneath this is a massive shale called
the Queen City. Below this is the Wilcox formation which is sands/shales
and lignites. Below this is the Midway shale a massive shale. Then comes
some marls, known as the Navarro/Taylor section, beneath this is the Austin
Chalk and below that is the Woodbine/Tuscaloosa shale.

Given this invariable order, why can't we use mathematics to correlate?
Because the thickness of each strata varies from South Texas to Louisiana.
Some wells have faults, which cause missing sections.

horizon a \
horizon b \
horizon c \horizon a
\horizon b

If you drill a well at position V you find no horizon a and only part of
horizon b. This makes mathematical correlation difficult because of the
missing section. I must use the well logs, the seismic and other info to
decide if this missing section is a fault or if it is an unconformity or a
In one place the Wilcox might be 2500 feet thick in another it might be
5000. This also makes sampling of any series difficult because when you run
a mathematical correlation, you don't have the top and base of the formation
matching in the two sequences. I wrote a program to try to mathematically
correlate gamma ray logs and ran directly into the variation in
stratigraphic thickness problem.

>Yes, I think a Christian should be willing to look
>at the rocks. It seems to me that the reason he
>would do so (besides the fun of it) is to assess
>the accuracy of the claims made in what he reads.
>However, if the claims in what he reads are not
>clearly and thoroughly presented, it is hard to
>make the assessment.

Find a local geologist and go with him to the field. Tell him what you want
to do and most will be delighted to help you and answer any questions with
you looking at the rocks.

No I haven't been on many
>trips with a live guide. I haven't seen many
>available except from park personnel who often
>haven't been that well informed in my experience.

unfortunately, you are correct here.

>I don't mind being candid about my conjecture of
>what the real situation is. I suspect that the
>degree of reliability in coarse correlations over
>large distances is higher than what several
>"creation" writers would have one believe. I
>also suspect that the degree of reliability in
>much of the less coarse correlation over great
>distances is considerably less reliable than
>many "mainstream" writers would lead one to
>believe. I find it hard to determine for myself
>where the true situation lies.

Come on into geology. Get a degree and go to work with us. We are on the
verge of an oil boom and there will be lots of money and employment.
However, I would warn you that when you go back to much of the Christian
community to tell them that what they teach doesn't match what you see, no
one will beleive you.

>Let me relate an experience. I was reading a paper
>claiming to show a tight correspondence between
>radiometric dates and dates from traditional
>non-radiometric methods (the name Evernden comes
>to mind without looking it up, which isn't
>essential here.) There was a long string of
>references supporting the data points in this
>correspondence. I found that one of these
>references was to a study in my state - my
>county in fact. I went to try to see for myself
>(so what I made a few questionable fence crossings).
>I could clearly see the radiometrically dated
>layer at this spot and could also see the excellent
>outcrop of the traditionally dated layers. What I
>couldn't see for myself was any trace of fossil
>content despite considerable exploring and poking.

This is one of the frustrating things. I was shown a secret trilobite site
by some professors once and was left there for a morning trying to collect a
fossil. I wasn't exactly sure what form the fossils were, and I didn't see
any. There were there by the hundreds when I was told what to look for and
shown one. One's eyes must know what to look for sometimes. I felt really
dumb for missing hundreds of fossils at my very feet.

However, in most cases such as the rest
>of the notable examples that you describe in the
>article, one is left wondering just how much of
>the evidence for the particular correlation is
>unquestionable and how much is in the eye of the

Until you follow the same horizon for long distances you may never know. One
has color, the bed above and below, the fossils, the lithology, the
sedimentological traits, ichnofossils and many other items to try to
determine the correlation. But it is too complex to reduce to mathematics.
In other words our mathematics and statistics is too simple.

What fraction of the earth's formations
>are so clearly traceable as those you describe?

I don't know. A very sizable fraction can be traced a long, long distance.
The Paleozoic rocks are easier to trace and can be traced further than more
recent rocks.

>To what extent do multiple examples of such
>clearly traceable formations occupy regions
>in common?

they kind of overlap like several card decks thrown one card at a time onto
the floor until the floor is covered. Only the cards are big.

Numerous such questions can be
>asked. Again, I am not critical of your article for
>not addressing these questions - I couldn't see how
>they could be given an adequate answer in a short
>article. I am saying that I haven't been able to
>find any place where they are addressed well.

As many people as are critical of me and what I write, I don't mind even if
you were critical. :-)
>Clearly a motivation for writing this is get a
>reaction from more knowledgeable folk as to whether
>a quantitative assessment of correlation reliability
>is to be found anywhere.

come up with an algorithm that can automatically decide on thickening and
thinning between various parts of the stratigraphy and can recognize
missing section and you will make a fortune.


Adam, Apes, and Anthropology: Finding the Soul of Fossil Man


Foundation, Fall and Flood