Donald T. Secor, Jr.

This recognition of Dr. Donald T. Secor, Jr. is an appropriate honor to his lasting contributions to understanding the geology of the Carolinas, his leadership in inspiring others in the field, and exemplary service to the Carolina Geological Society (CGS). Don served for two terms as President of the Carolina Geological Society, and as a leader of several Carolina Geological Society annual field trips.

Most of you have attended field conferences with Don and discussed the salient meanings of outcrops, although not always agreeing on the many aspects of the geology involved. If you have been in the field with Don, you know that he lives for field work and takes every opportunity to find himself there. This is the quintessential Secor. In the time that I have known Don, I have come to know a person who by training, education, and inclination is a brilliant structural geologist. But it was his love of geologic mapping that led him to lead the life of a field mapper. As an undergraduate at Cornell University, he started as a civil engineering student as he was proficient with the mathematical rigor engineers used. However, under the guidance of Charles Nevin, another renowned structural geologist, Don found his true calling in geology. Don spent two summers mapping in Vermont, which became his first map publication. Bitten by the field bug, Don’s next stop was Leyland Stanford Junior University (sorry, my favorite joke with Don, “you got a PhD at a junior college?”). At Stanford Don worked with George Thompson, a well-known crustal geophysicist. Instead of geophysics, Don went mapping in the Spring Mountains of Nevada. His dissertation was on the fold-and-thrust belt in the Spring Mountains of southern Nevada. This is a classic area in the Sevier orogenic belt, and his studies were published in the Geological Society of America Bulletin in 1974. When Don finished his PhD in 1963, George hoped that Don had gotten the field bug out of his system. Little did George know.

Don began his faculty career at USC in 1964, and before long he was in the field mapping. Don has a long association with CGS. He first served as board president in 1965 and again in 1985. He led his first CGS field trip in 1968 detailing his early work on the Carolina slate belt. Additionally, Don led CGS field trips in 1978, 1987, 1998, and 2015. Since 2000, I have joined Don on many CGS trips, and we became good friends and bus pals. One additional service Don performed was his volunteer work with the South Carolina Geological Survey. This was a mutually beneficial arrangement. He provided the Geological Survey with map data, and we worked on publishing his maps. The Survey benefited from Don with many interesting discussions in the field and the office. Even though he has stepped away from geology now, we still have a backlog of map data to produce several more quadrangle maps.

An early paper of Don’s titled: ‘Role of fluid pressure in jointing’ is one of his most cited publications. It is a key paper for understanding jointing in rocks and has important implications in the migration of ground water, hydrocarbons, and ore fluids. This paper is commonly cited and discussed in many textbooks on structural geology. In the area of Piedmont geology, one of Don’s biggest contributions was the recognition of trilobite fossils in the Carolina terrane. Although Don is quick to point out that he did not find the first fossil, it was a student involved with Don and Art Snoke’s field mapping class. Don had put a bounty of a case of beer for anyone who found a fossil. Many tried to claim the bounty, but without success until Sara Samson brought in a specimen. Follow-up work on the fossils showed that they had a Baltic affinity and were evidence that the Cambrian-age sediments in which the they occurred were not part of North America at the time of deposition demonstrating that the Carolina terrane is exotic to North America. One early result of his mapping efforts was three papers in the Geological Society of America Bulletin in 1986. This was the beginning of the end to the idea that the Carolina slate belt is too deformed to understand and initiated our modern understanding of the Alleghanian orogeny in the Appalachian hinterland. These three papers recognized that deformational phases based on observable structures could be correlated with the known orogenic events, and geochronologic studies provided evidence for developing a complex model of Alleghanian deformation. In the intervening years this model has been improved through detailed geochronologic studies, primarily U-Pb zircon dating, which Don has been an active participant. Don’s focus also shifted to understanding the structural significance of his field mapping in the Piedmont, and he used mathematical models to show how foliations develop in shear zones to form either normal- or reverse-sense crenulation cleavages. This model has a physical basis in the rocks of the Irmo shear zone, a regional dextral shear zone in the Carolina terrane.

Through these studies, Don has come to be recognized and highly respected as an expert in Piedmont geology; this status is evident by his authorship of overview and synthesis chapters in prominent publications such as the GSA DNAG Southern Appalachian and Geology of the Carolinas volumes.

Don’s interest in field work is evident in the mentorship he provided dozens of graduate students. The majority of his Masters’ students completed field projects that added to his growing understanding of the Piedmont, particularly the Carolina terrane in South Carolina.

Don Secor’s legacy in CGS is based on an extensive record of service to CGS. He has made lasting contributions to the understanding of the geology of the Carolinas, and he has provided inspiration and guidance to others in the field of geology. The Duncan Heron Lifetime Achievement award is a most suitable award to Don’s long and illustrious career.

C. Scott Howard

Chief Geologist, South Carolina Geological Survey