ON THE ROCKS PRESENTS

Field Trip to the Dotsero CrateR

Join RMAG for a blast-into-the-past field trip—study the products of the most recent volcanic eruption in Colorado.

 Rescheduled date: Sunday September 14, 2025

Trip Leaders: Wendy Bohrson, Professor, Colorado School of Mines Co-leader, Valerie Strasser, volcanology PhD candidate, Colorado School of Mines 

Trip Coordinators: David Schoderbek and Ron Parker 

SOLD OUT! 

Join the Waitlist

Trip Description

Dotsero Crater is the youngest and only “active” (erupted less than ~10,000 years ago) volcano in Colorado. It likely formed around 2200 ± 300 BC in a single eruption that included the formation of a crater, scoria cones, a lava flow, and a maar.

We will examine these features by initially viewing the crater from the south side of the rim. We will then amble along a rugged path to the north side of the rim, where we will directly examine the maar and scoria deposits. On our way back to I-70, we will also stop and examine the associated lava flow, which crosses I-70. We will also discuss the petrogenesis of the magmas, the dynamics of the explosive eruption that produced the maar, and the regional volcanological history.

Important Details

• First meeting point: We will meet at the Woolly Mammoth Park & Ride at 8:00 am, where we will carpool in 4-wheel drive vehicles.
• Second meeting point: We will meet again at the City Market in Eagle (City Market, 13 Market St, Eagle, CO 81631) by 10:30 am, depending on traffic. This will be a fuel and comfort stop, as City Market offers restrooms, coffee, food, and more. Additionally, there is a Sinclair gas station on the south side of I-70 in Eagle. This will be our last comfort stop until we return to City Market at the end of the field trip.
• At around 10:50am, we will caravan to Dotsero Crater. The road to our parking area is rough, so it would be best to drive a four-wheel-drive vehicle.
• We will park and walk to the south and north sides of the crater. We will likely be away from the vehicles for about 4 to 4.5 hours.
• Once we have concluded the crater part of the field trip, we will pile back into the vehicles and make a short stop at the lava flow.
• Stout hiking boots, gaiters (the trail is very dusty and pebbly), lots of water, lunch, and snacks are recommended. Sunscreen, sunglasses, a hat, and hiking poles will also be useful. Volcanic rocks can be quite sharp, so a pair of gloves may be useful as well.
• The total planned hiking distance will be ~2 miles, with some steep up and downhill hiking involved. 

Cost

• $ 50 Members
• $ 70 Non-Members (not a member? Join Today!)

Refunds

Refunds for the Dotsero Volcano Field Trip are available until September 1, 2025. After September 1, 2025, if you can no longer attend you can transfer your registration to another attendee or forfeit the trip costs.

Waivers

All registrants must fill out the Medical Emergency, Waiver and Release of Liability form. Those who fail to complete the form will not be permitted to attend the field trip.