2018 Field Trips

2018 Field Trips

April 21: Squaw Butte with Professor Ander Sundell of CWI

We will explore Lake Idaho sediments and Columbia Plateau basalt flows as we drive to the summit of the Butte; Ander contributed to the recently (2017) published geological map of the Butte. We will register at the Home Depot/Winco parking lot on State Street and Old Horseshoe Bend Road at 7:30 AM with departure at 8:00 AM. We will go out State Street to Highway 16, then up Hwy 16 through Emmett to the Squaw Butte road.  Most vehicles will be able to drive up the butte, but we’ll evaluate and carpool as necessary where it gets steep. Non-strenuous walking up to ¼ mile possible. Dress for the weather, bring lunch and plenty of water. Return to Boise by 5:00 PM No pre-registration required.

 May 5: Volcanic Features near Mountain Home

Field trip coordinator Steve Cox will lead this trip to view a number of interesting volcanic features in the Mountain Home area, including a ferro-magmatic basalt flow full of plagioclase crystals on I-84, the Crater Rings, Sheep Maar vent, Smith’s Crack, Eureka Cave, Teapot Dome and Cinder Cone Butte. This route will replicate part of the field trip from J. W. Shervais, et al., Geological Society of America Field Guide 6, 2005 (source URL is below). We’ll also discuss a a new theory of the Yellowstone Hotspot while looking out over the beginning of the Eastern Snake River Plain. Walking will be at your choice up to 1/4 mile, mainly at Crater Rings and Sheep Maar, other sites are close to parking. Registration will be at the Museum at 7:30 AM, with departure at 8:00 AM sharp. Dress for the weather bring food and drinks (a rest stop at the big truck stop at Mountain Home will provide provisions, if needed). No pre-registration required. Return to Boise by 5:00 PM.

A link to an article about Snake River Plain Volcanics:  Basalt and Rhyolite Volcanism WSRP

An important article too large to uplink to this page; copy the URL into your browser to go to the article:


 Here is an entertaining YouTube video that describes the long-lived Yellowstone Hotspot and the rotation of older calderas into Washington and Oregon, derived from the long URL article above: https://www.youtube.com/watch?v=MXEQeTg0Xww.

Here is a DropBox Link to the Hotspot article: https://www.dropbox.com/home/Public

 June 16: Gold Panning with the Idaho Gold Prospectors Association

We will return to Grimes Creek, one of the most famous sites of the 1862 Idaho gold rush, to pan with the IGPA on their claim. This is a kid-friendly trip and they have a “teaching pan” to show the youngsters the technique. There is a lot of history in this area and the prospectors love to share it.

We will register at the Museum at 7:30 AM with departure at 8:00 AM. We will go out Warm Springs Avenue to meet Highway 20 and then proceed to Idaho City for a rendezvous at the visitor center and then drive up to the claims. No vehicle restrictions. No strenuous walking. Dress for the weather, bring lunch and water. You can leave when your poke is full. No pre-registration required.

July 14: Jordan Craters with Nick Pollock, PhD candidate at BSU

(Almost Dr.) Nick will lead us to the Jordan Craters; a first time experience for IMMG field trips. Jordan Craters is a very recent volcanic event, often cited as 3,200 years old, consisting of spatter cones, lava flows and lakes, and lapilli. We will register at Winco on Meridian Road just north of I-84 at 7:30 AM, departing at 8:00 AM. We will go west on I-84 to Exit 33A (Karcher Road/Hwy 55) which we will follow to Marsing and the big Gem Stop station at the junction with Highway 95. This will be a rest and supply stop and an alternate registration point for west valley residents. Then we will proceed south on Highway 95 to Jordan Craters Road. There are no vehicle restrictions on the gravel road to the Craters.

You can return late to Boise or stay over in Jordan Valley with two options – the Basque Station Motel or the Flatiron B&B (early reservations are advised). Return to Boise will probably be between 6:00 – 7:00 PM. It will be HOT, so dress for the weather, bring lunch and plenty of water. You can walk as much as you like, but be aware that the lava beds are irregular and walking sticks are advised. No pre-registration required.

Here is an article about the Craters:

Jordan Craters

Here is Nick’s field guide: Jordan Craters_FieldGuide_2018

August 4: Vale to John Day with Mark Ferns.

Retired Oregon State Geologist and leader favorite Mark Ferns will take us along Highway 26 to John Day, looking at interesting volcanic features and some of the gold prospecting history of the area. This trip will have several options: return from John Day on Saturday; stay over Saturday night and return on Sunday; or stay over both Saturday and Sunday and visit the famous John Day Fossil Beds National Monument on Sunday, returning to Boise on Monday. The tour to the fossil beds is not guided, but the visitor center has good info on the several units of the Monument. If you choose to stay in John Day, early motel reservations are advised. There are three available – Best Western, America’s Best Value Inn, and  Dreamer’s Lodge. There are adequate restaurants and groceries available.

The trip will register at the Winco parking lot on Meridian Road just north of I-84 – turn right off of Main St. onto Central Drive – at 7:30 AM with an 8:00 AM departure. We’ll take the interstate to the big rest area just over the Oregon line for a rest stop and re-grouping; this could also be an alternative registration spot for west valley residents. From there we’ll get back on the interstate and take Exit 374 onto Highway 201 South to US 26 into Vale where we’ll meet Mark at the Sinclair Station on the west end of town. Dress for the weather, bring food and water. No extended walking is anticipated. Pre-registration is not required.

Here is Mark Ferns’ trip guideFerns Field Trip Guide 2018

A good website on the various formations found in the JDFBNM: https://www.nps.gov/joda/learn/nature/geologicformations.htm

Here is a brief guide to the John Day Fossil Beds NM: Trip Guide John Day Fossil Beds

September 15: Snake River Volcanics; Steve Cox and Dr. Terry Panhorst Co-leading

We will explore volcanic features along the Snake River and two sites near Bruneau; this will be a nice contrast to our May trip around Mountain Home as many of the sites will show impacts of river and ground water on volcanic activity. After a scouting trip on Sep. 6th, we decided that sites west of Grandview were either too repetitive, too hard to access, or too distant, so we decided to go to our old favorite, the alagal reef and a new site just down the road from there that has a very interesting feature (you have to come on the trip to learn what it is).

The trip will register at the Museum at 7:30 AM with a departure at 8:00 AM. We will head out on Warm Springs to Broadway, then merge onto I-84. We will have a mandatory rest stop at the Blacks Creek rest area. Then, resuming along I-84  we will exit at Simco Road, which we will follow the junction of Highway 167, turning right.  Leaving Highway 167 on Bennett Road, we will visit three sites north of the Snake River following Collett road, Gravel Pit Road and Big Foot Bar Road. Our last stop on this segment will use a somewhat rocky two track road for about 150 yards and then a benign sandy road to the parking area. We will have lunch under a grove of trees and will set up the “Ladies Loo Tent” here. After lunch we will return to Highway 167 to the junction with Highway 78 and the Grandview gas station/store for a rest stop before heading east toward Bruneau.

As always, dress for the weather, bring lunch and plenty of water. A couple of walks of about 1/4 mile give us the best views of some sites, so good shoes/boots and walking poles are advisable. Most of the off-highway roads are decent gravel; we can arrange local car pools at the one site noted above. No pre-registration required. Back to Boise by about 5:00 PM.

October 6: Don’t Take it for Granite: IMMG Geologist Coyote Short Leading

Our Idaho Batholith is not just one homogeneous body of granite, but was built by a number of individual plutons at different times. Coyote, assisted by her faithful sidekick Jannelle Wintersteen, have scoured the Atlanta Lobe in our area to point out the differing mineral compositions, crystal structures and unique signatures of the plutons that have contributed to the Batholith north of Boise and in the Garden Valley area.

We will register at the Museum at 7:30 AM with a short program at  the Museum at 8:00 AM. We will depart heading west across Boise on State Street to the Winco parking lot at the intersection with Highway 55 to reassemble the group. There will be a rest stop in Horseshoe Bend and at the Crouch City Park.  As always, dress for the weather, bring lunch and water. Extensive walking is not anticipated, No pre-registration required.

Links to Trip Route Notes, a document about components of granite, a geologic map of Boise County and a Bowen’s Reaction Series diagram are attached below; click on the link, then Save, and you can open in your computer.

October 6 Route Notes

Boise County Map

Bowen’s 2

Components of Granite