Reprinted from AAPG Bulletin, volume 50 (1966), number I (January)
It is with a sense of inestimable privilege that I speak on this occasion in acknowledgment of the debt I know every member of this audience feels all of us owe, and this Association owes, to our cherished friend, Honorary Member and former President-the late Arville Irving Levorsen. I do not exaggerate when I assert that all around the earth petroleum geologists held him in highest esteem. Among us who knew him personally, a similar high esteem blended with our warm affection.
W.H. Auden insists that among criteria of worth in a man, "no documents, no statistics, no objective measurements can ever compete with the single intuitive glance." But where shall we catch that "single intuitive glance"? Are his values to be discerned only in the personality of the man himself? Or are they reflected also by the fruits of his labors? I can not pretend to an intimate acquaintance with A.I. Levorsen, the man. It was "by his work" that I knew him. Can 1, then, have caught that "single intuitive glance" Auden hails as all-revealing? For many years Levorsen and I were friends. Yet it was never my good fortune to be closely associated with him. He was younger than I by nearly a half generation. Our respective centers of professional interest were always almost half the width of a continent apart, geographically. Nevertheless, my awareness of him has long been as vivid as his actual presence in the same room could have made it.
There is an old adage, which declares that every man writes his own epitaph. It is my thesis that Levorsen literally did just that; that his published writings, books, scientific papers-scores of titles distributed through time across the entire span of his professional career--constitute an epitaph as revealing as the composition of an intimate friend could be. It is this record-Levorsen's epitaph of himself-that I propose here briefly to explore.
I read in this epitaph a word-portrait of one who, above all else, was a student, a life-long student of the geology of petroleum. Yet immediately, I am aware of something of an anomaly in this student; it is that even as he himself learned, he taught others. While still a student, he was already a teacher. If we were to borrow a simile from the lore of the oil-finder, we might say that just as the favorable structural anomaly which develops penecontemporaneously with sedimentation often proves unusually productive of hydrocarbons, so Levorsen, teaching penecontemporaneously with his own learning, later contributed in unusual measure to the art of oil-finding.
In 1919, barely two years out of college, Levorsen, at work in western Louisiana, encountered for the first time (and quite by accident) the geology of the Tyler basin, situated just across the state line in East Texas. Already aware of the conspicuous outcrops of Woodbine Sand, hundreds of feet thick along the basin's western margin and around its northern end, Levorsen was startled when his party chief informed him that its eastern margin, tilted gently westward off the Sabine uplift, was totally devoid of Woodbine Sand!
This "single intuitive glance" at the Tyler basin plunged Levorsen into a fever of speculation. His imagination caught fire, not so much from the Woodbine wedge-out, exciting though that was, but from his realization of the control it must exercise over fluid movement in the basin. Levorsen did not stay in the South to participate in the future development that he immediately envisioned for the Tyler basin; he returned instead to the Mid-Continent, where his professional career already had begun to take root. Nevertheless, his mental image of that updip wedge-out of the Woodbine and its bearing on possible accumulations of hydrocarbons persisted. And he recalled it with undiminished clarity when, a little more than 10 years later, a wildcat well on a remote location in the Tyler basin--a location selected, incidentally, with total disregard of geologic consideration--discovered East
Texas, the largest of North America's oil fields.
This early experience with the Tyler basin provided Levorsen with standards and concepts.for his subsequent appraisals of sedimentary basins as possible hosts to hydrocarbons over most of the earth. Back in the Mid-Continent he found it difficult to fall again into step in the ranks of his profession. His fellow petroleum geologists appeared to him unanimous in their pursuit of a single narrow objective. They were all engaged in a hectic search for anticlines. Local structural deformation, expressed as an anticline or dome, was to them the only effective agency for trapping hydrocarbons. His own outlook gradually came to encompass a far broader vision. His mind filled with the vagaries of sediment deposition, of compaction, of diagenesis, and of stratification of sediments. He thought of facies changes, the gentle regional tilting of the strata of a whole basin of deposition with subsequent truncation following uplift, of reburial and resulting unconformities. To him, all these had become factors in trapping petroleum. And as his vision expanded, his objectives grew larger: he would discover not a single new oil field, but a whole new category of oil fields, a succession of new petroleum provinces!
This wider outlook on the problem of oil-finding only developed through time. Levorsen's successive publications document its progress. An early paper, "Convergence Studies" (1927), already reflects his interest in factors other than anticlines or deformation of strata. His study, "Greater Seminole District" (1929), based on his earlier "Geology of Seminole County,' (1928), devotes only a single page to structure, but discusses stratigraphy for three pages. He concludes in fact that, so far as the prolific pre-Pennsylvanian reservoirs at Seminole are concerned, the geologic structure is indeterminable. The flagrant tolerance by conservation authorities of "crooked holes," which deviated as much as 45 degrees from the vertical, made well records worse than useless. They showed differences as great as 600 feet in the elevation of the same bed in offset wells on 10-acre locations.
"Studies in Paleogeology" (1933) testifies to Levorsen's early interest in a technique he has labeled as "the keenest tool in the geologist's kit" for dealing with what Philip King has described as "the science of gently dipping strata." Paleogeologic maps became Levorsen's most valued approach to geologic problems.
In AAPG's "Problems of Petroleum Geology" (1934), a survey by Levorsen reveals dig a majority of all oil fields, and by far the bulk of all oil produced in the Mid-Continent, are associated with unconformities. This association he would emphasize repeatedly in subsequent papers.
"Stratigraphic Versus Structural Accumulations" (1936) introduces and defines the term "stratigraphic trap"' a concept Levorsen made common currency, not only among geologists but throughout the oil-producing industry.
Levorsen inspired, organized, and edited "Stratigraphic Type Oil Fields" (194 1), as a special publication by AAPG. It reasserts and documents his insistence that our largest oil fields--our giant oil fields--commonly are housed in stratigraphic traps.
In 1953, driven by his instinct to share with others what he had learned and thought about oil, oil fields, and oil-finding, Levorsen published the first edition of "Geology of Petroleum," his most ambitious venture. It is a stimulating handbook for the petroleum geologist, vibrant with the author's zest to quicken the tempo of oil-field discovery. In character, also, is the author's conclusion that the most effective aid to exploration for oil is a comprehensive understanding of the detailed geologic history of the area under study: its stratigraphy, sedimentation, deformation, and especially its fluid phenomena.
The emphasis on fluid phenomena as a control of oil accumulation in sedimentary basins, a control which Levorsen's earlier papers do not stress, reveals the deep impression made on the author by King Hubbert's analysis of theories of groundwater movement published in 1940. Hydrodynamics and its function in trapping oil took on more and more significance to Levorsen, until, in a recent paper he ranked it equal in stature with stratigraphy and structure as one of three principal factors in "The Geometry of the Oilfield Trap."
The slender volume, "Paleogeologic Maps" (1960), written, as the author declares, after a study that "has extended over 35 years:' is perhaps Levorsen's most finished and most scholarly piece of research. Useful as paleogeologic maps can be to the finder of oil, as Levorsen skillfully demonstrates, they also can be made to serve effectively in other, wider fields. With successive paleogeologic maps, Levorsen modifies, convincingly and significantly, the generally accepted configuration of "the continental backbone" of North America.
Similarly, with a series of paleogeologic maps of the Michigan basin and its environs, he shows that basin to be less a true geosyncline than a mere tectonic low or sag left undisturbed by differential linear uplift along surrounding positive axes.
The Paris basin, long believed by European geologists to have persisted as a closed basin of deposition since the early Mesozoic, is shown by Levorsen's paleogeologic studies to have existed as a separate basin only since the early Tertiary. Previously, it had been part--a westjutting lobe---of the large West German basin ever since late Paleozoic time.
Finally, Levorsen marshals persuasive evidence, in the form of paleogeologic maps on the same pre-Upper Carboniferous unconformable surface in Brazil and South Africa, to show that at the time this old surface was truncated, the respective coast lines of these two areas could not possibly have been so neatly fitted together as the champions of the "Theory of Continental Drift" would have us believe.
To Levorsen, a paleogeologic map portrayed a buried, unconformable surface, just as an areal geologic map portrays the present surface. He coined apt phrases to make paleogeologic maps come alive. They were "flash-backs" into geologic history, "phantom faces" of Mother earth, faces that persisted only a moment in geologic time, faces pieced together from "isolated glimpses of different segments commonly widely separated from each other. Viewed from beneath the plane of unconformity, the paleogeologic map also gave Levorsen "a worm's eye view" of the overlying stratigraphic units and their contacts. Through his device of paleogeologic maps, Levorsen visualized "layers of geology" squeezed between buried unconformable surfaces where "subtle structure" trapped the oil of the Mid-Continent, his best-beloved oil province.
Levorsen's genius for teaching enabled him so to express his ideas on the occurrence of oil, on the nature of oil fields, and on the art of oilfinding as to make them intelligible to all men. As a result, his presence as a speaker at their annual conventions was sought just as eagerly by the independent oil-producers as by his fellow geologists.
In recent years, Levorsen had found occasion more than once to protest vigorously a tendency he had sensed for the seasoned and competent geologist in the oil-producing industry to be drawn farther and farther away from the rocks. Ever more frequently he saw management select its most able geologist for "promotion" to an executive position. There, the ex-geologist would administer corporate affairs, while the search for new oil fields was left to a team of specialists. Prestige and salary rise faster and farther for the executive than for the geologist. Nevertheless, Levorsen insisted if new oil fields are to be found, there must be placed and maintained between the executive and the technical specialists in exploration, a trained, experienced geologist, intimately familiar with the rocks themselves. And that geologist must have time, imagination, and perspective to create in the mind's eye, where every new oil field is first discerned, the mental image that will direct the specialists to their next discovery.
Such is the epitaph Arville Irving Levorsen wrote for himself, as I read it. Epitaphs always terminate, so far as my observation has gone, with a conventional phrase. This phrase Levorsen could hardly provide. I venture now to add it: R. I. P. May he rest in peace!