The Many Layers of Laurentian

Sanctum laurentiensis and the traces of geological connections


Mark Mende

During this time, when a Zoom meeting has become ordinary, every now and then, they can be extraordinary. Such was the case, when four generations of St. Lawrence geologists crashed a presentation by University of Texas-Austin geology doctoral candidate and St. Lawrence alumnus Ben Rendall ’11. And, at the core of it all, was St. Lawrence James Henry Chapin Professor of Geology and Mineralogy Emeritus J. Mark Erickson.

When Rendall was a student, he did his senior thesis with Erickson, as well as a Senior Year Experience (SYE) with Antun Husinec, professor of geology. 

“Mark took me under his wing and helped change the course of my life. That’s really not an overstatement,” Rendall says. “He cares so much about his students. They’re like his kids.”

After getting his master’s degree at Idaho State University, Rendall began working at the ExxonMobil Upstream Research Company, where he collaborated on research with another Laurentian geologist, Charles Kerans ’77, the current chair of the Geosciences Department of the Jackson School of Geosciences at University of Texas-Austin and internationally recognized stratigrapher and researcher of carbonate sedimentary rocks.

True to the fabric of Laurentian connections, Kerans was also one of Erickson’s early student research assistants in the mid-1970s. So, it was only fitting that when Rendall decided to take a leave of absence to pursue his Ph.D., he would head to Texas and Kerans would serve as his advisor.

Kerans and Rendall believe there are many things that make the geology department at St. Lawrence special. First is the quality of learning it offers. Second is its intense connection to its students and to alumni. Another relates to the personality of the department, fostered by faculty like Erickson and Husinec, who strive to simulate professionalism and the experience of a large research institution at a small liberal arts college. Rendall has continued to weave in other Laurentians by employing geology students, now graduating seniors, Sonja Wolke ’20 and Kyle Gorman ’20 as research assistants on the fieldwork for his dissertation. 

“The fantastic thing for the students (at St. Lawrence) is that you’re basically like a grad student,” says Kerans. “You’re doing research; you’re writing papers, going out in the field.” He adds, “You always know that if you get students from St. Lawrence, they will be high quality.” The result is that St. Lawrence students who accept this responsibility are actually getting a more valuable experience as undergraduates.

Another case in point is Erickson’s recent article in the international journal Ichnos, formalizing research of fossil behavior of a previously unknown species that was dubbed Sanctum laurentiensis. Erickson began the research into evidence of the organism in the 1980s and, together with student research assistant Tim Bouchard ’07 some 20 years later, they named the new trace fossil. He explains that the name is sort of a geological double entendre, as the species inhabited the ancient landmass known as Laurentia and was identified by Laurentians.

The research duo performed the fieldwork in the region surrounding Cincinnati, Ohio, back in the early 2000s, examining colonies of Bryozoa, a phylum of aquatic invertebrate animals. The evidence left by the trace fossil represents not the actual organism, but the burrows it made into the Bryozoan skeleton nearly 450 million years ago. Erickson and Bouchard believe the trace makers of Sanctum were small arthropods that lived in those burrows during the day and emerged at night to feed.

“That indicates the organism making the burrow had some smarts,” says Erickson. “If true, it also means it had one or more types of visual predators from which it needed to hide during the day—400 million years ago!” he adds.

Erickson credits working with student researchers such as Kerans, Rendall, and Bouchard as one way to advance everyone’s scholarship. “I got the stimulation of their thinking and the discussion back and forth,” he says, “and the students benefitted from having to develop original thinking and their own set of ideas.” 

Valuing the dialogue of contemporary geological research continues to bring Laurentian geologists together, which brings us full circle to Rendall’s recent Zoom presentation. Kerans decided to surprise him by inviting Rendall’s mentors Erickson and Husinec, as well as Rendall’s next-generation mentees, Wolke and Gorman, making it four generations of geology from St. Lawrence. 

“It was a great surprise,” Rendall says, observing the many layers of Laurentians.