Geomorphology and dynamics of a coastal transgressive dune system, central California

ABSTRACT

The Callendar dunes are located within the Santa Maria dune complex in south-central California and have been studied repeatedly since the pioneering work of Bowen and Inman in the 1960's. Previous conceptual models of the system’s Holocene evolution relate variations in dune morphologies to changes in sediment supply and sea level. In the years since their studies, conceptual frameworks of coastal and continental transgressive dune systems provide useful avenues for re-visiting the morphodynamic history of the Callendar dunes. Our study presents grain size and dune spacing data collected by Tchakerian and Mulligan in 1981, while working under Orme as graduate assistants. These data, when considered in light of the more recent conceptual frameworks mentioned above, suggest that the Callendar dunes may exhibit some elements of self-organization. With this in mind, we apply a conceptual model of coastal transgressive dune systems to help elucidate some of the historical morphodynamics influencing the modern arrangement of morphologies at the Callendar dunes.

KEYWORDS:

• Coastal transgressive dunes
• South-Central California
• quaternary geology

Data availability statement

The data that support the findings of this study are available from the corresponding author, PB, upon reasonable request.

Acknowledgments

The authors thank Dr. Orme for his numerous contributions to our discipline, and mentorship of dozens of professional earth scientists. Without Dr. Orme’s efforts, it is likely the Callendar dunes would remain relatively unstudied and unknown outside the off-highway vehicle community. We also thank Dr. Kevin Mulligan for assisting Tchakerian in collecting the sand samples in 1981. Finally, we thank Drs. Jean Ellis and Ronald Dorn for their thoughtful comments and feedback.

Epilogue in memoriam

I owe my academic career to Professor Antony R. Orme. As a senior undergraduate student at UCLA, Tony (and Amalie) invited me to take his graduate level coastal dunes class in 1981. That seminar eventually led me to do my MS under Tony’s supervision at the Santa Maria Dune Complex (the Pismo Dunes) in central California. It became very clear during the seminar that much work needed to be done in coastal dune research and aeolian geomorphology in general. Many of us now in academia owe our immersion in aeolian geomorphology to Tony’s coastal dune seminar. After finishing my MS thesis and with Tony’s encouragement, I then undertook my dissertation work, once again under his guidance, on the geomorphology and chronology of aeolian dunes in the Mojave Desert. My first article was with Tony – we presented our joint work of the coastal dunes of the lower Pacific Coast (from central California and Baja California) at the 17^th Annual Binghamton Geomorphology Symposium on Aeolian Geomorphology in Guelph, Canada in 1986. As I am about to retire from academia, it is very emotional and personal for me that for my last article, I am coming back home to the Pismo Dunes, to revisit some of the coastal dune systems that Tony first articulated to me during that seminar, and to add some new ideas to his original contributions. For me, Tony remains the ultimate teacher, mentor and pedagogue and I will always cherish my professional and personal friendship with him and his family.

Vatche Panos Tchakerian, 22 January 2021

Disclosure statement

No potential conflict of interest was reported by the author(s).