Came across this from Answers in Creation. Not to be confused with Answers in Genesis.

Why I left Young-earth Creationism
by Glenn R. Morton
Copyright 2000 by Glenn R. Morton. This may be freely distributed so long as no changes are made to the text and no charges are made to the reader.

For years I struggled to understand how the geologic data I worked with everyday could be fit into a Biblical perspective. Being a physics major in college I had no geology courses. Thus, as a young Christian, when I was presented with the view that Christians must believe in a young-earth and global flood, I went along willingly. I knew there were problems but I thought I was going to solve them. When I graduated from college with a physics degree, physicists were unemployable since NASA had just laid a bunch of them off. I did graduate work in philosophy and then decided to leave school to support my growing family. Even after a year, physicists were still unemployable. After six months of looking, I finally found work as a geophysicist working for a seismic company. Within a year, I was processing seismic data for Atlantic Richfield.

This was where I first became exposed to the problems geology presented to the idea of a global flood. I would see extremely thick (30,000 feet) sedimentary layers. One could follow these beds from the surface down to those depths where they were covered by vast thicknesses of sediment. I would see buried mountains which had experienced thousands of feet of erosion, which required time. Yet the sediments in those mountains had to have been deposited by the flood, if it was true. I would see faults that were active early but not late and faults that were active late but not early. I would see karsts and sinkholes (limestone erosion) which occurred during the middle of the sedimentary column (supposedly during the middle of the flood) yet the flood waters would have been saturated in limestone and incapable of dissolving lime. It became clear that more time was needed than the global flood would allow.(See http://www.seg.org/publications/geoarchive/1996/sep-oct/geo6105r1336.pdf for an article showing an example of a deeply buried karst. For a better but bigger (3.4 meg) version of that paper see http://www.netl.doe.gov/publications/proceedings/97/97ng/ng97_pdf/NG4-1.PDF

One also finds erosional canyons buried in the earth. These canyons would require time to excavate, just like the time it takes to erode the Grand Canyon. This picture was downloaded from a site which is now gone from the web. It was http://ic.ucsc.edu/~casey/eart168/3DInterpretation/Deltain3d1.gif

I worked hard over the next few years to solve these problems. I published 20+ items in the Creation Research Society Quarterly. I would listen to ICR, have discussions with people like Slusher, Gish, Austin, Barnes and also discuss things with some of their graduates that I had hired.

In order to get closer to the data and know it better, with the hope of finding a solution, I changed subdivisions of my work in 1980. I left seismic processing and went into seismic interpretation where I would have to deal with more geologic data. My horror at what I was seeing only increased. There was a major problem; the data I was seeing at work, was not agreeing with what I had been taught as a Christian. Doubts about what I was writing and teaching began to grow. Unfortunately, my fellow young earth creationists were not willing to listen to the problems. No one could give me a model which allowed me to unite into one cloth what I believed on Sunday and what I was forced to believe by the data Monday through Friday. I was living the life of a double-minded man--believing two things.

By 1986, the growing doubts about the ability of the widely accepted creationist viewpoints to explain the geologic data led to
a nearly 10 year withdrawal from publication. My last young-earth paper was entitled Geologic Challenges to a Young-earth, which I presented as the first paper in the First International Conference on Creationism. It was not well received. Young-earth creationists don't like being told they are wrong. The reaction to the pictures, seismic data, the logic disgusted me. They were more interested in what I sounded like than in the data!

John Morris came to the stage to challenge me. He claimed to have been in the oil industry. I asked him what oil company he had worked for. I am going to let an account of this published in the Skeptical Inquirer in late 86 or early 87. It was written by Robert Schadewald. He writes,

"John Morris went to the microphone and identified himself as a petroleum geologist. He questioned Morton's claim that pollen grains are found in salt formations, and accused Morton of sounding like an anticreationist, raising more problems than his critics could respond to in the time available. Morris said that the ICR staff is working on these problems all the time. He told Morton to quit raising problems and start solving them. "Morton chopped him off at the ankles. Two questions, said Morton: 'What oil company did you work for?' Well, uh, actually Morris never worked for an oil company, but he once taught petroleum engineering at the University of Oklahoma. Second, How old is the Earth?' 'If the earth is more than 10,000 years old then Scripture has no meaning.' Morton then said that he had hired several graduates of Christian Heritage College, and that all of them suffered severe crises of faith. The were utterly unprepared to face the geologic facts every petroleum geologist deals with on a daily basis. Morton neglected to add that ICR is much better known for ignoring or denying problems than dealing with them."

It appeared that the more I questions I raised, the more they questioned my theological purity. When telling one friend of my difficulties with young-earth creationism and geology, he told me that I had obviously been brain-washed by my geology professors. When I told him that I had never taken a geology course, he then said I must be saying this in order to hold my job. Never would he consider that I might really believe the data. Since then this type of treatment has become expected from young-earthers. I have been called nearly everything under the sun but they don't deal with the data I present to them. Here is a list of what young-earthers have called me in response to my data: 'an apostate,'(Humphreys) 'a heretic'(Jim Bell although he later apologised like the gentleman he is) 'a compromiser'(Henry Morris) "absurd", "naive", "compromising", "abysmally ignorant", "sloppy", "reckless disregard", "extremely inaccurate", "misleading", "tomfoolery" and "intentionally deceitful"(John Woodmorappe) 'like your father, Satan' (Carl R. Froede--I am proud to have this one because Jesus was once said to have been of satan also.) 'your loyality and commitment to Jesus Christ is shaky or just not truly genuine' (John Baumgardner 12-24-99 [Merry Christmas]) "[I] have secretly entertained suspicions of a Trojan horse roaming behind the lines..." Royal Truman 12-28-99

Above I say that I with drew from publishing for 10 years. I need to make one item clear. It is true that I published a couple of items in the late 80s. The truth is that these were an edited letter exchange I had with George Howe. When George approached me about the Mountain Building symposium, I told him I didn't want to write it. He said that was ok he would write it, give it to me for ok and then publish it. Since it was merely splicing a bunch of letters together, it was my words, but George's editorship that made that article. To all intents and purposes I was through with young-earth creationist (not ism yet) because I knew that they didn't care about the data.

But eventually, by 1994 I was through with young-earth creationISM. Nothing that young-earth creationists had taught me about geology turned out to be true. I took a poll of my ICR graduate friends who have worked in the oil industry. I asked them one question.

"From your oil industry experience, did any fact that you were taught at ICR, which challenged current geological thinking, turn out in the long run to be true? ,"

That is a very simple question. One man, Steve Robertson, who worked for Shell grew real silent on the phone, sighed and softly said 'No!' A very close friend that I had hired at Arco, after hearing the question, exclaimed, "Wait a minute. There has to be one!" But he could not name one. I can not name one. No one else could either. One man I could not reach, to ask that question, had a crisis of faith about two years after coming into the oil industry. I do not know what his spiritual state is now but he was in bad shape the last time I talked to him.

And being through with creationism, I very nearly became through with Christianity. I was on the very verge of becoming an atheist. During that time, I re-read a book I had reviewed prior to its publication. It was Alan Hayward's Creation/Evolution. Even though I had reviewed it 1984 prior to its publication in 1985, I hadn't been ready for the views he expressed. He presented a wonderful Days of Proclamation view which pulled me back from the edge of atheism. Although I believe Alan applied it to the earth in an unworkable fashion, his view had the power to unite the data with the Scripture, if it was applied differently. That is what I have done with my views. Without that I would now be an atheist. There is much in Alan's book I agree with and much I disagree with but his book was very important in keeping me in the faith. While his book may not have changed the debate totally yet, it did change my life.

References
For an example of a seismic karst during the middle of the geologic column go to

http://seg.org/

Select 'publications' from that page

Select 'Geoarchives'

Select '1996'

Select 'September and October'

Select 'pdf' from 3-D seismic reflection tomography on top of the GOCAD depth modeler
Jean Luc Guiziou, Jean Laurent Mallet and Raül Madariaga

Scroll down to page 6-8 on the acrobat reader. These are pages 1341-1343 of the original journal.

There you will see 3d seismic data that shows evidence of a subaerial erosional event supposedly in the middle of a world wide flood!