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FT-04 Examination of Codell and Niobrara Outcrops, Northern Front Range

Rocky Mountain Association of Geologists (RMAG)

Saturday, 25 September 2021, 8:00 a.m.–5:00 p.m.  |  Fort Collins, Colorado

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Course Content

Unconventional petroleum reservoirs productive in the Denver Basin include the Niobrara Formation and the Codell Sandstone. Both units are characterized by low porosity and permeability. These units are well exposed in outcrops along the west flank of the basin and will be the subject of this field trip.

Dinosaur Ridge

The Codell is Turonian in age and consists of silty, shaly, bioturbated sandstones. The outcrop sections generally display coarsening upward cycle of sediments. Low angle cross stratified beds are present in the lower and in places middle parts of the Codell and are interpreted to represent hummocky cross stratification. The bioturbated sands are interpreted as lower shoreface to shallow shelf deposits. The upper few feet of Codell in the Fort Collins Holcim quarry area is cross stratified and this is thought to represent middle shoreface deposits.

The Niobrara is Turonian to Campanian in age and consists largely of chalk and marl beds. The formation is divided into the lower Fort Hays and the upper Smoky Hill members. The chalk beds are high in CaCO3 content. The B and C chalks are the primary targets of horizontal drilling. The Fort Hays with its high calcium carbonate content is the target for mining operations to make cement. The chalks and marls are deposited in relatively deep water (500 ft or greater).

Itinerary Roster

The trip will consist of two main stops:

  1. Holcim Quarry; Fort Collins, CO: Examine Niobrara Formation and Codell Sandstone
  2. Cemex Quarry; Lyons, CO: Examine Niobrara Formation stratigraphy & discuss fracture systems

Transportation will depart from the Denver Convention Center at 8:00am and return at 5:00pm


$250 per person
Field Trip Guidebook


FT-04 Examination of Codell and Niobrara Outcrops, Northern Front Range
Niobrara Outcrops
Fort Collins, Colorado
United States


William Brown Hawkins William Hawkins 2021-2021 Technical Trainer, Geologist, Pix4D, USA
Stephen A. Sonnenberg Stephen Sonnenberg 2021-2021 Professor, Colorado School of Mines, USA