Objectives
This Thompson Field Forum will build on synergistic land sessions to showcase field research advances and remaining research questions in this iconic field laboratory. Karl Karlstrom and Laura Crossey will coordinate field stops and discussions of incision data, neotectonics, and lava dam studies. Eugene Humphreys will coordinate geodynamics discussions to debate the hypothesis for mantle-driven uplift of the Colorado Plateau–Rocky Mountain region. David Shuster will coordinate discussions of thermochronologic studies of now-eroded landscapes. Kelin Whipple will coordinate geomorphology discussions of bedrock strength controls on river and canyon morphology and debate evidence for steady versus transient incision.
This research has global reverberations in terms of Cenozoic neotectonics, landscape evolution, and mantle-driven dynamic topography. The objective is to stimulate next steps on these topics.
Description
River trips allow several types of interactive sessions: (1) discussions on the outcrop; (2) “plenary” discussions at morning and evening seminars; and (3) short talks and discussions on boats while floating past key areas. Each participant will be asked ahead of time to prepare and lead a seminar or outcrop discussion, with poster-type materials to hold up or pass out. The eight-day river trip covers 280 miles from Lees Ferry to Pearce Ferry such that there is also ample time for one-on-one and small-group informal discussion as we travel downriver. Distance is measured in river miles (RM) downstream from Lees Ferry. On average, we cover about 35 RM per day (four hours per day of motoring through spectacular geology). Numerous hour-long to half-day hikes are planned. Key half-day hikes may be dated strath-to-strath incision history locations at Kwagunt, Palisadea, and Elves Chasm; high terraces near Unkar Rapids; travertines on Tonto Platform near Hermit Creek; dated landslide river diversions near Deer Creek Falls; and lava dam dates and incision points in western Grand Canyon.
Logistics
The trip will be run by commercial charter rafting company Grand Canyon Expeditions. Participants arrive in Las Vegas, Nevada, USA, on Friday, 13 Sept., in time for an evening orientation meeting at 7 p.m. An early start with a bus takes us to Lees Ferry for a midday launch on 14 Sept. Camping gear, dry bags, and life jackets are provided to participants. The trip would take out at Pearce Ferry midday on Saturday, 21 Sept., and participants are bused to Las Vegas. Grand Canyon Expeditions uses a jet boat to pick up participants at Separation Canyon (RM 240), which allows more rapid boat transit across the abrupt boundary between the Colorado Plateau and Basin and Range provinces at RM 270 enroute to the take out at RM 280 and discuss the “Muddy Creek constraint.” There will be a final get together that evening, but many participants may want to proceed to Phoenix that evening (a 1.5-hour flight) to check in for the GSA Annual Meeting icebreaker.
Preliminary Agenda
| 13 Sept. |
Arrive in Las Vegas; group orientation at Residence Inn Las Vegas Hughes Center (hotel covered in trip cost); |
| 14 Sept. |
Bus to Lees Ferry and launch midday; |
| 15–21 Sept. |
Group will travel downriver 20–50 river miles (RM) per day, camping on beaches. Possible itinerary:
- Sept 14: RM 0–30: Lees Ferry knickpoint and rock strength discussions;
- Sept 15: RM 30–66: Incision rate measurements and Little Colorado River;
- Sept 16: RM 66–94: Thermochronology of eastern Grand Canyon;
- Sept 17: RM 94–120: Hike to Tonto Platform, carving of inner gorge;
- Sept 18: RM 120–137: Hike Surprise Valley landslide;
- Sept 19: RM 137–178: Muav Gorge and mantle-uplift discussions;
- Sept 20: RM 178–225: Lava dams and Hurricane-Toroweap faults and fault-dampened incision;
- Sept 21. RM 225–280: Western Grand Canyon thermochronology and Muddy Creek constraint; and
- 21 Sept. Take out at Pearce Ferry and bus to Las Vegas, arriving by 4–5 p.m. (hotel covered in trip cost).
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Attendees and Estimated Costs
The registration fee will cover all lodging, including camping gear, all meals, and field trip transportation. The lodging is made up of hotel for two nights (double occupancy) and camping. Participants are responsible for their own transportation to and from Las Vegas, and optional additional travel insurance. Cost estimate: US$2,800–US$3,200 per person. Please check this web page for updates. Once the registration fee is finalized, participants will pay a first half deposit by 1 Jan. 2019 and a final payment by 1 June 2019.
Application and Registration
| 1 July 2018 |
Applications accepted |
| 1 Sept. 2018 |
Application deadline |
| 1 Oct. 2018 |
Notification of acceptance (or wait list) |
| 10 Dec. 2018 |
Registration deadline |
All interested participants must apply and be accepted to attend. We invite U.S and international researchers, young investigators, and students to apply. To apply, please email Karl Karlstrom () with a letter of intent that includes a statement of your research interests, the relevance of your recent work to the themes of the field conference, the subject of a proposed presentation, and your complete contact information. Students and early career professionals may apply for scholarships by adding a paragraph about their need for scholarship support. Participants must commit to attending the full conference. Group size will be limited to 28 participants.
Near Phantom Ranch, Grand Canyon. Photo by Laurie Crossey.
Synergistic “land session” meetings
22–25 September 2019:
GSA 2019 Annual Meeting & Exposition, Phoenix, Arizona, USA.
Thompson Field Forum participants are encouraged to attend, present at, and serve as panelists for the GSA theme sessions that immediately follow the trip.