Motley View: Engineering Geology as a Vital Phase in the GeoSpectrum

I have written and lectured often on the GeoSpectrum of professionals, spanning Engineering through Geology. Recently, I wrote an invited Editor’s Commentary (Engineering Geology- A Vital Phase of GeoEngineering) for the March/April 2009 Engineering Geology edition of the Geo-Strata magazine of the Geo-Institute of the American Society of Civil Engineers. The 11,000-plus  members of the Geo-Institute are primarily Geotechnical Engineers, and so the piece was directed at them, but almost any geoprofessional within the GeoSpectrum will understand what I wrote; which is why the post title has broader scope that the Commentary title.

The Commentary reproduced here is substantially the same as the version that appeared in the magazine, less a nice picture I provided and some possibly slight editorial changes.


I am a Geological Engineer, a discipline little known to most American Geotechnical Engineers, and often misunderstood to be the same as Engineering Geology – although many Geotechnical Engineers do not understand Engineering Geology either. But, Engineering Geology (and Geological Engineering) are vital to Geotechnical Engineering practice, being lively segments of the wide field of endeavor once gracefully called the Applied Earth Sciences, which connect engineering and geology in the phase sequence:

Engineering–Civil Engineering–Soil/Foundation/Rock/Groundwater Engineering– Geological Engineering–Engineering Geology–Geology

These few phases were once close enough that geologists and engineers could understand each other. Soil/Rock/Groundwater Engineering became Geotechnical Engineering, the field I studied in the 1970s, in which there was recognition of the importance of rock and soil as geological materials. But with the evolution of academic and technical specializations, the “Geo” understanding in “Geotechnical” is now so diminished and removed from “technical” that most Geotechnical Engineers need Geological Engineers and Engineering Geologists to tell them what, just a few years ago, they likely knew for themselves. How many recent Geotechnical Engineering graduates have even had a college course in Engineering Geology? By the way, saying “I know enough geology to get by” does not count as an education in Engineering Geology, but is more likely an assured ticket to eventual ground failures. Without a basic understanding of geology, or the intuition and imagination of the Engineering Geologist, geotechnical engineering analysis is, to me, lifeless.

Many Geotechnical Engineers refer to Engineering Geologists and Geological Engineers as “Geologists,” which is unjust: how would Geotechnical Engineers like it if they were routinely characterized as plain “Engineers”? But the distinctions, as presented in the linear-phase sequence, are easy enough to understand. Geologists are scientists, often with little background or interest in engineering applications. Engineering Geologists are most often geologists who have had additional training and geotechnical engineering and geoenvironmental education, but who are generally not eligible for Professional Engineer licensure. Geological Engineers are engineers with academic backgrounds in civil, geotechnical, and mineral/petroleum engineering coupled with considerable geology; they are eligible for licensure as Professional Engineers and, often, as Professional Geologists as well. And, of course, you know what Geotechnical Engineers are:  primarily engineers, with a lot of dirt, some rock, and a bit of groundwater mixed in.

If Engineering Geologists and Geological Engineers seem different to Geotechnical Engineers, it’s because they are – the way geologists and engineers think and work tends to separate them. Engineering Geologists spend lots of time in the field, and are often happiest when scrambling on slopes, stumbling through poison oak, and working at remote sites that tourists would pay much money to visit! Engineering Geologists also have inherent skills to visualize and create possible geological models from scant site observations. I say “inherent” because to become a successful geologist requires vivid imagination, spatial thinking, and non-linear reasoning.

These are traits that are uncommon in engineers, who naturally tend be better at systematic, logical, and quantitative reasoning than geologists. Further, communication between geologists and engineers can be difficult. With more than 40,000 geological terms, the language of Geology is a foreign babble compared to the lean lingo of engineering, although Engineering Geologists are well equipped to translate the geological language and characterizations into engineering terms. And not to forget my own field: Geological Engineers are often better at two-way translations given their rich backgrounds in both engineering and geology.

In case you do not understand how important Engineering Geology is to Geotechnical Engineering, take a few minutes to demonstrate to yourself how challenging is the job of subsurface characterization. To start the demonstration, put your hands together in front of your face, palms outward and separated by a pencil-wide gap. Pretend that the gap is the lens of a “slit camera.”  Peer through the gap and take half a dozen random mental “slit photographs” of your surroundings. Now e-mail those shots to a colleague across the world (or even next door) and ask him/her to reconstruct your surroundings from the images. Impossible? Well, we Engineering Geologists and Geotechnical Engineers alike, do the seemingly impossible every day when we characterize unseen volumes of the subsurface on the basis of a few borings or outcrop maps! Compare the difficulty of our job to that of the Structural Engineer: we work with limited data collected from large volumes of subsurface materials that have spatially-varying and widely-ranging properties. But, the Structural works with buildings with largely predictable behaviors, constructed of well-understood manmade materials. Is it any wonder that we Geos have to envelope our uncertainty with generous factors of safety?

Engineering Geologists and Geological Engineers are trained to both perform challenging site characterizations and understand how imperfect the geological models are. Regrettably, many Geotechnical Engineers no longer know enough geology to fully appreciate the latter.

Given my unusually broad background in the Applied Earth Sciences, I would rather that the once relatively simple linear-phase sequence between geology and engineering had not split into so many specializations, many of which seem remote from geology, although intimate with computer science. Accordingly, I believe that we all benefit from the role and umbrella of the Geo-Institute of the ASCE, embracing the breadth of geotechnical engineering and its allied fields. We could further acknowledge our vital need for Engineering Geologists and Geological Engineers (and Rock Engineers, Engineering Geophysicists, Hydrogeologists, etc.) by referring to our practice disciplines as being part of GeoEngineering (although, to my ears, the expression “GeoEngineering” sounds abrupt compared to the pleasing cadence of “Applied Earth Sciences”). Still, “GeoEngineering” nicely juxtaposes Geology and Engineering and neatly shortcuts the complex, 3D network of specialist offshoots that now exist between the simple linear phase sequence that once connected Engineering and Geology.

About Ed Medley

Ed Medley has been on a random walk for over 50 years. Many scribbles and snapshots at this site are from his vagabond transits; others are from his decades of international experience in geological and geotechnical engineering, academia, and mineral exploration prospecting.
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