ON THE ROCKS PRESENTS

Pennsylvanian-Permian eolian/fluvial system along the northern Colorado Front Range: Part II

 SATURDAY September 6, 2025

Trip Leaders: Marshall Deacon, John Webb, Steve Fryberger, Ginny Gent

RMAG Coordinator: Ronald Parker, Tom Dimelow

Trip Description

Return to the Permian! Part II will explore the northern reaches of the Permian system along the northern Colorado Front Range. For this trip, we will be extending our examination of the Lyons Sandstone and the underlying Ingleside and Fountain formations northward from outcrops at Lory State Park that we examined last September, visiting iconic exposures of these formations and observing regional facies and depositional environment transitions associated with deposition adjacent to the Ancestral Rocky Mountains. This is where the Ingleside formation meets the sea, the Lyons meets its end, and the Lykins gets salty. Lots to see from high frequency climate-eustatic induced cyclicity, excellent reservoir and seal rocks, and plenty of fluvial, eolian and marine clastics and carbonates to keep us busy.

*Photos by Ron Parker

Logistics

Participants will meet at Me Oh My Coffee and Pie shop in Laporte, CO (3310 W County Road 54g, Laporte, CO) to top off coffee and restroom use. The first field trip stop will be just north of Horsetooth damn near Bellevue along the irrigation ditch. This will be an overview stop of the regional Permian (Wolfcampian – Leonardian) geology and up close with compound dune deposits in the Lyons Sandstone. The second stop will be along Hwy 287 near Livermore CO. A classic road cut of the Ingleside marine to continental depositional cycles. The third stop will be an examination of a sandy interdune/sand sheet complex of the Lyons Sandstone along CR80 and the fourth and final stop will be at Red Mt. open space. This stop will involve a relatively flat hike of approx. 2 miles to examine the Ingleside cycles, two Lyons sandstone beds, the overlying Blaine anhydrite and the Salt Creek anticline. We will be back at the cars by 4:00 for the ~2 hour drive back to Denver.

Cost

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

Refunds

Refunds for the Pennsylvanian-Permian Eolian/Fluvial System Along the Northern Colorado Front Range Field Trip are available until August 25, 2025. After August 25, 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. Those who fail to complete the form will not be permitted to attend the field trip.