Dr. Marcus Gary is a karst scientist who specializes in conducting hydrogeologic investigations to expand the understanding of karst forming processes, and study the implications that karst geology has on natural resource management. Dr. Gary received his Ph.D. in hydrogeology from the Jackson School of Geosciences at The University of Texas at Austin in 2009, and a B.S. degree from the same institution in 2001. His dissertation focused on defining the geological processes that formed one of the deepest phreatic cave systems in the world, Sistema Zacaton. This multi-disciplinary research included studies utilizing geophysics, geomicrobiology, hydrology, field mapping, geochemistry, and numerous related topics. Most notably, Sistema Zacaton was explored by the DEPTHX probe, also known as the Deep Phreatic Thermal Explorer. This instrument was developed and tested with over 5 million dollars of funding from NASA, and Dr. Gary served as the co-project PI. The DEPTHX probe produced an unprecedented spatial dataset used to characterize the 318 meter plus deep underwater cave system. Dr. Gary also worked for 8 years as a hydrologist for the U.S. Geological Survey, 4 years as a private environmental consultant, and is now currently a senior hydrogeologist for the Edwards Aquifer Authority in San Antonio, Texas in addition to teaching Applied Karst Hydrogeology at the Jackson School. Prior to his career in geosciences, Dr. Gary was a commercial diver, working for over 8 years in the offshore oil industry, conducting marine archeological surveys, managing hyperbaric medical facilities, exploring underwater caves, and recovering ICBMs for the U.S. military in the south Pacific. He is the proud husband and father to his wife Robin and sons Jake and Mac.

Areas of Expertise

Karst Hydrogeology


Research Locations



Current Research Programs & Projects

Trinity-Edwards Inter-Formational Flow


Graduate Students

Jenna Kromann (Co-supervisor)
I am interested in studying the dynamics of surface water-groundwater interactions and karst hydrogeology. Currently, I am researching the Nueces River in Uvalde County, investigating the interaction between surface water and groundwater. Focusing on: estimating the amount of recharge into the Edwards Aquifer using innovative technologies, determining the controls on gains and losses in the river, and investigating the effects of gravel alluvium on aquifer recharge. Then combining collected data to develop a water balance for this river system and model.


Collecting depth profiles at the Poza Verde

Photos of research of the Sistema Zacaton karst area

Collecting depth profiles at the Poza VerdeStaging for a dive at CaracolDEPTHX being lowered into El Zacaton.Sheck Exley and Jim Bowden after discovering Zacaton was deep.Camping area at La Pilita.Deploying a decompression system for dive exploration.Aerial view of El Zacaton (left) and the resurgence of Nacimiento.Poza Verde with the Miocene granitic peak of Granadillas in the background.Floating islands are called El ZacatonEl Zacaton