top of page




View of the Big Lost River and high peaks of the Lost River Range from ISU Geosciences’ Lost River Field Station near Mackay, Idaho.

2021 Conference Registration Information


TRGS will hold its 46th Annual Field Conference July 29 – Aug. 1, 2021 at Lost River Field Station (LRFS) ( 15 miles north of Mackay, Idaho. The geology near Mackay includes thrust faults and folding associated with the Pioneer thrust system, enigmatic low-angle faults with multiple stages of both thrust and normal movement, the Pioneer metamorphic core complex and coeval Eocene Challis Volcanic Group, and the active Borah Peak normal fault which forms the boundary between the Big Lost River Valley and the Lost River Range to the northeast.  The field station is directly west of Borah Peak, the highest summit in Idaho. Geologically significant post-Belt Supergroup but pre-Windermere Mesoproterozoic strata east of Challis are also a topic of interest.  The Empire Copper Mine, itself responsible for the settlement of Mackay in the 19th century, is being actively explored for new minable resources and will be visited in a field trip.  


Conference organizers are Paul Link and Dave Pearson.

***** Covid19 Concerns*****

All participants must be vaccinated for Covid-19 virus. Be advised that you participate in this conference at your own risk. Please bring your face mask and be prepared to wear it.


Meeting Location

Our venue will be at the Lost River Field Station, north of Mackay, Idaho (see map below).


The Field Station is at 5930 Bartlett Point Road, off of Old Chilly Road, south of the Trail Creek road to Sun Valley, west of US Highway 93, and on the south side of the Big Lost River. The field station has showers, cell and land line phone access, internet, and a hot tub. Free on-site camping and rustic trailers are available but limited.  If you intend to camp, stay in a trailer, or bring an RV to the field station please notify Paul Link (208-317-3946, before June 5 to reserve a spot.  We cannot guarantee space will be available to late registrants. 


Mackay motels and RV parks

  • Wagon Wheel Motel & RV Park, 809 W Custer Rd, Mackay, ID 83251  (208-588-3331)

  • White Knob Motel & RV Park, 4255 US-93, Mackay, ID 83251(208-588-2622)

  • Bear Bottom Inn412 Spruce St, Mackay, ID 83251(208-588-2483)

  • Challis Hot Springs, 5025 Hot Springs Road, Challis ID 83226  (208-879-4442), is about 30 miles north of LRFS.  The site offers camping with a large hot pool, on the banks of the Salmon River.

  • The nearby Challis National Forest and extensive Bureau of Land Management land offer free camping. 



Schedule and Logistics


On Thursday night after dinner (7 pm), there will be a TRGS Board Meeting at 8 pm.   


The “official” TRGS meeting format is informal and begins Friday morning with invited talks followed by half-day afternoon field trips on Friday afternoon. Saturday and Sunday have all-day field trip options, and Monday and Tuesday will have informal day-long post conference

field trips. Registration will be late afternoon Thursday, and all Friday morning.


An informal poster session will begin Friday morning and, weather permitting, posters can be taped to the outside of the field station through Saturday night. For further information or to help with the conference, contact Paul Link ( or Dave Pearson (


Breakfasts Friday, Saturday, Sunday and Monday may be purchased for $10 each. 


Lunches will be prepared by meeting participants, with their cost included in the field trips. If you are a vegetarian, lunch options are available.  Please check the box on the registration form if you are a vegetarian. 


Dinner Thursday, Friday, and Sunday is $15 for each meal. 


There will be a catered BBQ dinner Saturday evening provided by Bear’s Western Barbeque of Hailey that can be purchased for $25. 


We will supply drinks, including soft drinks for the field trips.  


Transportation to various field sites will be by small group/individual private vehicle. Some field trips have rough roads and/or limited parking and vaccinated individuals are encouraged to share a vehicle when possible.



Thursday July 29, 2021

3 – 6 pm    On-site registration at Lost River Field Station   

7 pm   Dinner     TRGS Business meeting at 8 pm


Friday July 30, 2021

7:30 – 9:00 am    On-site registration continues   Posters can be taped outside.

8:00 am Breakfast      


Friday morning agenda

9:00 am - Paul Link Conference Chair

9:10 am - Ben Crosby-ISU Geoscience Chair, Welcome

9:20 am - Ryan Anderson and Donna Delparte ISU Field Camp at Lost River Field Station 

9:35 am - TRGS Awards and Announcements


Technical presentations: Talks (20 min) scheduled at 25-minute intervals, 5-minute discussion


  • 9:45 am Jim Sears — Connecting Idaho and Montana to northeast Siberia in a Proterozoic supercontinent


  • 10:10 am Kendra Murray et al. — Low-temperature thermochronology reveals Neoproterozoic rift origin of the Rocky Mountain Front Range, Colorado


  • 10:35 am Dave Pearson and Paul Link — Post-Belt Supergroup Mesoproterozoic to Cambrian rocks of the Leaton Gulch area, east of Challis, Idaho


  • 11:00 am Jim Vogl — Overview of the Pioneer metamorphic core complex, central Idaho


Lunch 11:30 am.  Look at posters outside.  Make Sandwiches from the spread provided.

Field Trips leave at 12:15 pm. 


A1. Paul Link and Brad Burton— Cross section of the Cordilleran orogenic belt over Trail Creek road north of the Pioneer Core Complex, central Idaho; Roadside field trip with minor walking. 


A2. Paul Wetmore and Chuck Connor---The subsurface architecture of the Lost River Valley and changes in the dip angle of the Lost River Fault. Roadside trip, minor walking.

A3.  Keian Moran and Ryan McDermott:  Geology, historic and present activity of the Empire mine project, Custer County, Idaho, Minimal walking


Dinner at 7 pm


Saturday July 31

7:00 am Breakfast and prepare lunches

8:30 am: Trips leave


B1. James Vogl, Megan Borel, Rory McFadden, Carolina Ortiz-Guerrero:  A tale of two detachments: Structural relationships and strain along the northwest margin of the Pioneer Mountains metamorphic core complex.  Significant 6 mile walk on and off trail


B2. Glenn Thackray and Braedon Warner:  The Big Lost River Floods and Glaciation of

East-Central Idaho.  Moderate walking


B3.  Zachery M. Lifton: Lost River fault and the Borah Peak Earthquake fault scarp; Minor walking over uneven terrane


BBQ by Bear’s Western BBQ and Catering at 7 pm.  Chicken, Pork Ribs, Cole Slaw and Corn Bread. 


Sunday August 1, 2021

7:00 am: Breakfast and prepare lunches

8:30 am: Trips depart


C1. Elizabeth S. Petrie and Bradford R. Burton:  Kinematics, polyphase deformation and graphite distribution within the Pioneer fault-zone, Little Fall Creek, western Pioneer Mountains.  3 mile walk on trail up Little Fall Creek.  Exposures are off trail


C2. David M. Pearson and Paul K. Link: Post-Belt Supergroup Mesoproterozoic to Cambrian rocks at Leaton Gulch. We will visit the enigmatic Leaton Gulch area of the northernmost Lost River Range, where Cambrian Wilbert Formation, post-Belt Mesoproterozoic rocks, and an interpreted fragment of the fill of the Beaverhead impact crater are exposed.  Drive to the mountain top over sketchy roads.  Moderate walking off trail.


C3. David E. Stewart, Colleen Elliot, and Reed S. Lewis:  Eocene Challis volcanic rocks near Challis, Idaho; Ignimbrites, vitrophyres, lava flows and volcaniclastic strata near Challis.  The walk to the Malm Gulch petrified forest involves 30 minutes of easy trail walking in a hot gulch; the other stops are road cuts.


Dinner at 7 pm


Monday August 2, 2021 

7:00 am Breakfast.

If you elect to join the informal Field Trip today (or tomorrow), no food or hydration is provided. Be sure to sign-up a day or two prior to departure for head counts for the trip leader, and plan for your needs. **This area can be very hot and dry.**


Trip D1 - Informal Field Trip lead by George Grader: Rock Creek and Devonian sandstone channels in Jefferson Dolomite with optional climb of Borah Peak, Lost River Range.  Off-trail 3-mile traverse, with climb of about a thousand feet, with optional summit climb.


Tuesday August 3, 2021

Trip E1 – Informal Field Trip lead by Dave Stewart: Jim Canyon Challis volcanic section, North Fork of the Big Lost River. Off-trail climb of 1,500 feet.



Registration for the meeting includes a hard copy of 2021 Northwest Geology, edited by David Pearson. 

Idaho State University students who register for the conference by June 5 can have their meal and field trips cost covered by a donation to the ISU Geoscience Department.  Please make reservations on the form, and check the ISU Student Box. 

Direct questions about the field conference or accommodations to Paul Link ( Additional conference information may be posted on the TRGS webpage ( or the TRGS Facebook page. Contact Sandy Underwood ( if you are interested in helping out at the conference.


REGISTER BY MAIL: Complete the pdf registration form and pay by check. If you intend to camp or bring an RV to the field station please notify Paul Link (208-317-3946, before June 5 to reserve a spot.  After that, availability of camping spots cannot be guaranteed. Other registrations please postmark by July 20.

Send to: Tobacco Root Geological Society, P.O. Box 118, Butte, Montana 59703-0118.


REGISTER ONLINE*: Online registration opens on May 21. After registration opens, complete the online registration form and either pay by PayPal or send a check for registration fees to Tobacco Root Geological Society, P.O. Box 118, Butte, Montana 59703-0118. Please be sure to print and bring your confirmation email. Please complete the online registration form no later than July 20.


Online registration is the preferred method of registration for accurate attendee contact information, trip registration, and meal selection. Registration deadlines are in place to secure adequate food for the catered meal.


All field trip participants, including leaders, must register for the conference. Field trip leaders do not need to pay for the field trip(s) they are leading. Friday, Saturday, and Sunday. Field trip registration includes a lunch. Please note that there are two places on the form where you can contribute to the scholarship fund of the TRGS – by purchasing a conference T-shirt or by making a direct contribution to scholarships.

bottom of page