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What I learned as a geophysicist wannabe

When I was an undergraduate my favourite professor, Dr Oliver T Hayward, gave me what I thought was the most challenging field project of the entire class. I was to traipse across Texas collecting data on High Plains Gravels. This was not the first challenge he had given me for his class assignments: another gem had been to determine the herding behaviour of dinosaurs. To put this in context, this was before you could search online and find oodles of information on almost any topic.

Approaching the assignment of High Plains Gravels with a less-than-enthusi­astic attitude, I set out to look at every knoll and plateau across the western plains of Texas, spending a fortune on gas and cursing Dr Hayward every mile of the way. Slowly, inevitably, my attitude changed. I learned that there had been a complete inversion of topography — low areas had accumulated quartzite gravel and then resisted erosion.

I became a detective, solving a geological mystery. There is no source for the quartzite gravels for hundreds of miles, so where did they come from? How did the gravels travel so far? Why had they resisted erosion so well? It was a fascinating project from so many perspectives.

You may wonder what this has to do with being a geophysicist wannabe. The answer is that I learned the critical importance of looking for all the answers to a problem, wherever they might be, and the importance of not limiting myself by selective thinking. There are so many geological puzzles that can be better defined and answered through geophysical interpretation. Or more precisely, through the geological interpretation of geophysical data.

One of my favourite tools has been to use millisecond timeslices through merged 3D datasets to visualize basement fault reactivation and determine how it affects stratigraphy through geological time. For example, you might see how reactivated faults create carbonate margins that develop over time due to subtle highs. Perpendicular to the platform highs you may see where orthogonal fault systems have created avenues for bypass sediments shed off into the localized basins, potentially leading to a number of potential plays such as deepwater fan deposits. A case of a simple method providing profound insights.

Geophysics is such an integral part of the geological sciences, and you do not have to be a certified geophysicist to gain geological understanding by digging into geophysical data. The opportunities for solving geological problems and gaining geological insight are endless. Ask questions. Learn about data acquisi­tion. Go to processing meetings. Read up on the new techniques. Pay attention to pitfalls. Every geologist should look at seismic data.

Time and motion

Three kinds of uncertainty