POST-MEETING FIELD TRIP

(CRESTONE to DENVER)

JUNE 3, 2016

Featuring:

The PostMeeting Field Trip (all day Friday, June 3) travels from Crestone to the Best Western Plus Airport hotel near the Denver International Airport. The trip provides transport back to Denver for those Registrants who traveled to Crestone on the bus of the PreMeeting Field Trip, or anyone else who wants to return to Denver. The Field Trip bus will leave from the Desert Sage Restaurant in Crestone after breakfast on Friday, at 8 am. Estimated arrival time in Denver is 6 pm.

post-meeting route map

Google Earth map of the route (blue) of the PostMeeting Field Trip from the Crestone bottom center to Denver International Airport (upper right. Red lines show major Quaternary normal faults of the Rio Grande Rift.

The Field Trip will start the day by crossing Poncha Pass on the Sangre de Cristo horst and entering the Upper Arkansas Graben, the highest-elevation part of the Rio Grande Rift. Between Poncha Springs and Leadville, the valley floor rises from 2300 m to 3000 m, while the rift-flank uplifts rise to 4380 m. We will spend the morning visiting fault scarps of the Sawatch Fault Zone and the comparing fault traces mapped by aerial photographs in the 1980s, versus LiDAR-based mapping in the past 5 years. The entire route of the field trip is covered by these 1-m LiDAR DEMs.

Faults mapped by various techniques and authors in the southern graben of the Upper Arkansas Valley. We will visit several scarp sites on the Field Trip.

Faults mapped by various techniques and authors in the southern graben of the Upper Arkansas Valley. We will visit several scarp sites on the Field Trip.

Lunch will be on the banks of the Arkansas River at River Park in Buena Vista. Buena Vista is the headquarters of the lucrative river rafting industry in Colorado, made possible by late Pleistocene outburst floods and their huge transported boulders.

One of many large boulders lying on late-glacial outwash terraces downstream of the failed ice dam. These have been cosmogenically dated as being deposited ca. 15-17 ka.

One of many large boulders lying on late-glacial outwash terraces downstream of the failed ice dam. These have been cosmogenically dated as being deposited ca. 15-17 ka.

After lunch we travel up the flood terraces to the moraines that dammed the Arkansas River at 17 ka and 19 ka, and to the lake formed by the ice dams. The rim of the late-glacial lake is marked by distinctive low-gradient landslides typical of rapid drawdown of a reservoir.

rapid drawdown landslide

Passing through the historic downtown of Leadville, we cross Fremont Pass and the Climax Molybdenum Mine, and descend to Interstate Highway 70 for the drive back to Denver. We will ascend to the Continental Divide but pass beneath it in the 2.7 km-long Eisenhower Tunnel (elevation 3400 m). After passing through several mining-era ghost towns, we should arrive back in at the Best Western Plus airport hotel at ~6 pm.