|
by John C. Crowell
Perry Ehlig, an outstanding geologist
and professor, died unexpectedly on December 26, 1999. He has
contributed significantly to understanding the complex regional geology
of southern California, especially of the basement rocks and
displacement history of the San Andreas Fault system. He leaves a
published record of some 40 papers, many dealing with the Vincent and
related thrust systems and the origin and history of the underlying
Pelona-Orocopia-Chocolate Mountain greenschists. He was especially an
inspirational and beloved professor at California State University, Los
Angeles, and influenced the careers and viewpoints of numerous
undergraduates, and he was the caring advisor of many graduate students.
Perry was also a highly regarded consulting geologist, and worked on
many projects involving engineering, ground water, and landslide
problems. Perry Ehlig has scrutinized rocks in nearly every range and canyon from north of the Transverse Ranges to south of the Mexican border, with a special focus on the San Gabriel Mountains, Mojave Desert, borders of the Salton Trough, and along several strands of the San Andreas Fault system. California geologists would frequently call upon him to comment upon what rocks were where. In addition, he studied the Palos Verdes landslide over many years, providing one of the longest records known of the activity of a single landslide by any one scientist. His publications provide a lasting record of both his careful fieldwork and mapping, and of his associated petrographic and geochemical studies. Geology and teaching were his way of life and joy, and he indefatigably pursued them. Perry Lawrence Ehlig was born on May 23, 1927, on a small farm in the San Gabriel Valley, in what today is Temple City, a part of the Los Angeles megalopolis. He was the youngest of three children of Max Carl and Jeanette (Rentchler) Ehlig. His father came to the United States from Germany and served in the US Army during World War I, including a time in Siberia. He was well educated and could converse in several languages. Military service led to deterioration in his health, and he died in 1940. Perry's mother also was a musician and on occasion played the violin in the Los Angeles Philharmonic Orchestra. She died while Perry was in high school. Perry took to music as well, and his family recalls Christmas gatherings when he would play his trumpet loudly. As he was beginning high school, Perry took flying lessons, and hoped to become a pilot. In fact, he received his private pilot's license at age 15 before he could get his automobile driver's license. In aiming for pilot training, he enlisted in the US Army Air Corps in July 1944 and began serving in 1945. He was shipped to Louisiana for basic training. Unfortunately, the pilot-training program was discontinued, so he was assigned to Chanute Field, Illinois, for education in meteorology. He graduated as a weather forecaster and for a short time was an instructor before assignment to Hamilton Field, north of San Francisco. He was discharged from the Army in January, 1949. He served with the Army (Air Force) Reserves from 1949 to 1953. Much later, in 1966, when he was a recognized engineering geologist, he was sent to Vietnam as a consultant with the rank of lieutenant to help the Corps of Engineers locate gravel deposits for construction projects. Perry attended Pasadena City College after his army discharge and then entered the University of California, Los Angeles (UCLA) in the fall of 1950, to major in geology. He was awarded the BA degree in 1952, and the PhD in 1958 although most of his dissertation research was completed by 1956. This research involved the study of an exceptionally rugged part of the San Gabriel Mountains, with elevations ranging from a low of about 3,000 feet to the summit of Mount Baldy at 10,064 feet. He mapped the Vincent thrust in its type region where pre-Tertiary continental basement rocks of many types and ages, including Precambrian, are emplaced above the Mesozoic Pelona Schist, a unit largely of ensimatic origin. During Perry's undergraduate time at UCLA, I recall with awe his vigor, endurance, and enthusiasm as he ran about over steep slopes, mapping as he went. On a spring field course in 1951 where I was an instructor, he brought his bride, Marilyn May Winbigler Ehlig along as a field assistant. Marilyn would supplement his field notes as Perry galloped from outcrop to outcrop, yelling his observations back to her. Perry began his professional career as a geologist for Robert Stone and Associates in 1954, undertaking engineering geology projects in the Los Angeles region. During the summer of 1954, he conducted reconnaissance mapping for Texaco in central Nevada, in the vicinity of the newly discovered Railroad Valley oil field. His career as a memorable teacher really began, however, in the fall of 1956 when he was appointed assistant professor of geology at California State College at Los Angeles, now Cal State University, Los Angeles. Perry was one of the founders of the department at CSLA and taught there for 43 years, for 36 as a regular faculty member until his formal retirement in 1992, and thereafter as a volunteer professor emeritus until his untimely death after a brief and unexpected illness at the end of 1999. During his academic career he served as department chairman, assistant to the Vice President-Academic Affairs, and acting Dean. His classes included physical geology, geological mapping, optical mineralogy, metamorphic petrology, structural geology, advanced structural geology and tectonics, summer field geology, geology of California, tectonic problems of southern California, and engineering geology. In addition he supervised twenty three graduate students in their Masters degree endeavors, and accompanied each to his or her field area, many repeatedly. He was always available at his office or home and would enthusiastically go to the student's field area, weekdays or weekends, holidays or not. As an example of his generosity, his gifts largely supported the 10-week summer field course. Comments from Perry's former graduate students reveal how much he influenced their lives: “I remember Perry for his extraordinary generosity to his students and for his strong desire to see them succeed.” “He was totally passionate about what he did for a living.” “Perry contributed much to understanding the tectonic development of southern California and to its landslide hazards and mitigations.” “ In the field “he beat everyone to the top of the mountain, and back down again, and made geology a wonderful adventure.” “Perry was intelligent, diligent, accessible, and sharing. He wanted others to have the same thirst for geology that he had.” “I cannot recall another petrologist with such a solid grasp of geophysics, tectonics, structural geology, field geology, and engineering geology.” “My clearest recollection is sitting around a campfire in Baja California, talking with Perry about what igneous petrology might contribute to solving tectonic problems.” “His passion and enthusiasm for geology were inspiring and invigorating to all of us students.” Former students and colleagues recall midnight dips into desert irrigation ditches, or arriving at campsites after dark only to follow him at a run along a contact by moonlight, or friendly tussling into cholla cacti just beyond the campfire's glow as the geologic discussion waned. He set very high professional standards for himself and his students, but always had fun 'doing geology'. Perry Ehlig was a California registered geologist and engineering geologist, concerned primarily with landslide, groundwater, fault, and earthquake problems, mainly in southern California. For example, he studied sites for two nuclear generating stations, and for a hydroelectric plant. We worked together on a proposed tunnel beneath the central Transverse Ranges to bring water from the southern San Joaquin Valley to the Los Angeles region, a project now in abeyance. The tunnel was planned to cross both the Garlock and San Andreas faults at depth, and we enjoyed speculating on what these sheared and broken zones would reveal if studied in detail during the tunneling. Over many years he gave freely of his time and expertise to the investigation of active landslides in the Palos Verdes Hills and guided mitigation efforts. He also served as a member of the County of Los Angeles Engineering Geologists Review and Appeals Board. Ehlig was a Fellow of the Geological Society of America and a member of the Association of Engineering Geologists, American Association of Petroleum Geologists, American Geophysical Union, American Mineralogical Society, Society of Economic Paleontologists and Mineralogists, American Association for the Advancement of Science, and the National Association of Geology Teachers. On many occasions he led field trips for sections of these organizations. His investigations of the Vincent thrust system and the tectonically underlying Pelona Schist in the San Gabriel Mountains stand out among his recorded achievements. He led the way in demonstrating that the body of greenschist was laid down originally as a thick section of sediments and volcanic rocks upon ancient ocean floor during Jurassic and Cretaceous time, and then was carried eastward beneath a thrust system that emplaced continental rocks, viewed as part of a subduction zone. He was among the first to show inverted metamorphism, with a record of higher temperatures above those somewhat cooler. He also demonstrated that earlier structural displacements, carrying the schist body downward to the east were overprinted by those suggesting a much later reversal of shear direction. In time this led to recognizing that the uplifted and exhumed mass of schist was a type of core complex and that the uplift was related to widespread detachment faulting beneath much of southern California. His writings also deal with similar metamorphic and tectonic relations of the Orocopia, Chocolate Mountain, and Rand Schists. During all of these investigations, he has backed up his conclusions with careful petrological and geochemical studies in both the continental plates above the fault systems and within schist bodies beneath them. Ehlig has also contributed significantly to understanding the displacement history of strands of the San Andreas Fault system. With students he demonstrated that a Late Miocene volcanic center of distinctive rapakivi-textured quartz latite porphyry, located on the northeastern side of the San Andreas Fault, was the likely source of debris shed southwestward along a valley, a valley with its band of sediment now displaced dextrally about 240 km. This band constitutes the Mint Canyon Formation in the Soldedad Basin, and is in turn displaced dextrally about 60 km by the San Gabriel fault to the Caliente Formation at the head of the Cuyama River drainage. The narrow swath of volcanic debris constitutes the best “geological line with piercing points” yet recognized for maximum dextral slip on the combined San Andreas-San Gabriel system. In addition, Ehlig has mapped carefully along reaches of the San Gabriel fault within the rugged San Gabriel Mountains and demarcated its split into north and south branches with dextral slip on each, and mapped later faults that have crosscut these branches. Ehlig has followed the growth of the Palos Verdes landslide complex through several decades, and through these studies has added much to understanding the mechanics of the sliding, and the influence of groundwater and bedrock structure upon its evolution. Perry Ehlig cherished his family and included them in fun outdoor activities. He leaves behind his wife Marilyn and their large family: two daughters and three sons and nine grandsons and two granddaughters. His "family", in addition, includes a legion of geologists and others who were students of his and admiring colleagues. We will indeed miss him. SELECTED BIBLIOGRAPHY OF PERRY L. EHLIG1968 Causes of distribution of Pelona, Rand, and Orocopia Schist along the San Andreas and Garlock faults, in, Dickinson, W. R, and Grantz, A., eds., Proceedings of the Conference on Geologic Problems of the San Andreas Fault System, Stanford, California, Stanford Publications in the Geological Sciences, v. 1l, p. 294-305. 1975a Basement rocks of the San Gabriel Mountains, south of the San Andreas Fault, in Crowell, J. C., ed., San Andreas fault in southern California: California Division of Mines and Geology Special Report 118, p. 177-186 1975b (and Ehlert, K. W., and Crowe, B. M.) Offset of the Upper Miocene Caliente and Mint Canyon Formations along the San Gabriel and San Andreas faults, in Crowell, J. C., ed., San Andreas fault in southern California: California Division of Mines and Geology Special Report 118, p. 83-92. 1981a Origin and tectonic history of the basement terrane of the San Gabriel Mountains, central Transverse Ranges, in Ernst, W. G., ed., The geotectonic development of California; Rubey Volume 1; Englewood Cliffs, New Jersey, Prentice-Hall, p. 253-283. 1986 The Portuguese Bend landslide: its mechanics and a plan for its stabilization, in Ehlig, P. L., compiler, Landslides and landslide mitigation in southern California: Geological Society of America Cordilleran Section, Guidebook and volume, p. 181-190. 1987 Portuguese Bend landslide complex, southern California, in Hill, M. L., ed., Geological Society of America, Cordillera Section, Centennial Field Guide, v. 1, p. 179-184. 1988a Characteristics of basement rocks exposed near the Cajon Pass Scientific Drill Hole: Geophysical Research Letters, v. 15, p. 949-952. 1988b Geologic structure near the Cajon Pass Scientific Drill Hole: Geophysical Research Letters, v. 15, p. 953-956. 1988c (with Barth, A. P.) Geochemistry and petrogenesis of the marginal zone of the Mount Lowe intrusion, central San Gabriel Mountains, California: Contributions to Mineralogy and Petrology, v. 100, p. 192-204. 1993 (with Dillon, J. T.) Displacement on the southern San Andreas fault, in Powell, R. E., Weldon, R. J., II, and Matti, J. C., eds. The San Andreas Fault System: Displacement, Palinspastic Reconstruction, and Geologic Evolution: Boulder, Colorado, Geological Society of America Memoir 178, p. 199-216. |
