The Gist of our Geology

Free talks explain this valley’s landscape, and also why Mars is rusty, the state of modern cosmology, and plates versus plumes.

BY lila Edythe
PHOTOGRAPHY BY Bradly j. boner

TETON COUNTY LIBRARY’S Ordway Auditorium is packed. Every seat is taken, and people stand against the back and side walls. The crowd includes teenagers and their parents as well as senior citizens. The auditorium’s double doors are open so latecomers relegated to the lobby can at least hear some of what is going on. The reason everyone’s here? A bimonthly public talk presented by Geologists of Jackson Hole. This one is about the geology of the Gros Ventre Mountains, the range on Jackson Hole’s eastern side and often overlooked because it is not as jaggedly spectacular as the Tetons.

While visually outclassed by the Tetons, the Gros Ventres are geologically more interesting. Or so I’ve heard. I’m at this talk to learn if that is true and, if so, the hows and whys. But first I need to find a seat.

The Gros Ventre talk is my first Geologists of Jackson Hole program. Being a newbie, and never guessing that a talk about the Gros Ventres would draw a standing-room-only crowd, I make the mistake of arriving only a couple of minutes before its posted six o’clock start time. When I first walk into the room, two thoughts run through my head: 1) It’s not cool for whatever group using the room earlier to run over their allotted time, and 2) Maybe I’m in the wrong place. But then I see maps of the Gros Ventre in the front of the room and a single open seat in the back row.

While Geologists of Jackson Hole often brings in speakers from the University of Wyoming, Idaho State, and the University of Utah, locals like Bridger-Teton National Forest North Ranger District recreation supervisor Linda Merigliano; her husband, Mike Merigliano, a research plant ecologist and former forest manager; Susan Marsh, BTNF recreation staff officer from May 1988 until she retired in February 2010; and BTNF trails supervisor Tim Farris, among others, lead this program. Combined, the night’s speakers have more than a century of hiking and exploring in the Gros Ventres, which cover an area one and a half times the size of the Tetons and include the 317,874-acre Gros Ventre Wilderness.

Linda Merigliano gets the talk going, immediately addressing one of the things I’m here to find out. “One of the reasons the Gros Ventres were designated a wilderness were their unique expressions of geology,” she says. Well then. Mike Merigliano adds, “This is a range that is more than the sum of its parts. With a few exceptions, none of the parts are that interesting on their own but finding them all together makes for a very interesting mountain range.”

Mike then launches into talk of schists and shales. This could be boring. But since it’s accompanied by photos of remote parts of the range I’ve not yet had the opportunity to explore, it’s not. The photos make the talk as much an armchair adventure as a geology lesson. “These talks are given at a high level and get into the details of the science,” says Geologists of Jackson Hole co-vice president John J. Hebberger Jr. “The only thing we encourage speakers to do is to nontechnicalize the jargon. One of the biggest surprises for me is how open to truly complex topics people in this community are.”

Two hours after sitting down, I’ve got the answers to “how” and “why” the Gros Ventre Range is a geological superstar. I’ve also got a curiosity to check out more of these free public talks. With the exception of December, when organizers take a break, there are two talks every month.

“I CAN’T SAY we had a brilliant and complete plan when we started these talks,” Hebberger Jr. says. “But we certainly never expected the audiences to get as big as they have. If the auditorium at the library were larger, there are times we could have well over 150 people in the room.”

When it first formed in the mid-1980s—“there were a bunch of geologists here in town who got together to talk shop and rocks and have lunch,” says John Willott, the group’s president—the gathering was comprised of professional geologists, some still working and others retired. Today, anyone willing to pay the annual twenty-dollar membership dues (thirty-five dollars for a couple) and “with an interest in the world about them, the whole universe” can become a member, Hebberger Jr. says. There are about two hundred members, and they enjoy access to member-only lunches and field trips, the latter both nearby (Sunlight Basin) and far away (Scotland). You need not be a member to enjoy the bimonthly talks, like the Gros Ventre one, that are the most popular of the group’s offerings.

These public programs evolved out of Geologists of Jackson Hole’s desire “to offer something to the community rather than just to ourselves,” Hebberger Jr. says. Willott adds, “Our underlying mission for all that we do is to educate the public on how the earth works. We’re fortunate that earth science incorporates aspects of so many other sciences—biology, chemistry, physics, astronomy. All of these things need to be used to understand the world around us. What we’re able to bring under the umbrella and have people interested in is incredibly diverse.”

Many programs look at and explain some aspect of local geology, but “we work very hard on having talks from general-interest astronomy to deep earth,” Willott says. The night after my interview with Willott, the topic of the group’s public talk is “Magnetism, Magmatism & Ice: Traveling to the South Pole to Understand Magnetic Field Reversals.” Sadly (seriously!) I already have plans. But I put two later programs, “Life After Death: Whale Fall Scavenging Successions” and “The Challenges of Forecasting Snowfall Around Jackson Hole,” in my calendar.

Nuts & Bolts

Geologists of Jackson Hole’s public programs are typically from 6 to 8 p.m. the first and third Tuesdays of every month except December, when none are held. Talks are free and held in the Ordway Auditorium at Teton County Library (125 Virginian Lane). For the current schedule, go to geologistsofjacksonhole.org.