photo by Randy Tomer, courtesy of the Deschutes Land Trust
The Deschutes Formation ranges in age from approximately 7.5 to 4 million years old and consists of volcanic deposits and associated sediments that were predominately sourced from the east flank of ancestral High Cascades. While the Deschutes Formation is present over a large portion of the upper and middle Deschutes Basin in the greater Bend area, to the south it is buried under younger volcanic deposits sourced from the Cascades Range to the west and Newberry Volcano to the south. North of Bend the Deschutes Formation comprises much of the surface geology and is especially well exposed in the canyons of the Deschutes and Crooked Rivers and Whychus Creek. The Deschutes Formation is of particular interest because, not only is it the best way to understand the evolution of the ancestral, High Cascades, but it serves as the major groundwater aquifer in the area.
This field trip will visit the Alder Springs trail head, on the Crooked River National Grasslands, and do a 3-mile hike with an elevation change of 400 feet to the banks of Whychus Creek. Along the way we will see numerous outcrops showing the transition from the volcanics dominated to the sedimentary dominated facies of the Deschutes Formation and its importance as an aquifer.
This field trip is scheduled for Friday September 13, from 9 am to 3 pm. The hiking is rated as moderately challenging. The hike into and out of the canyon at Alder Springs has some relatively short but steep sections and it can be hot this time of the year. This field trip is suitable for all levels of background in geology. This will be a good introduction to those who are not familiar with the Deschutes Formation or these outcrops, and for those who are, this is a good chance to become reacquainted and engage in some lively geo-discussions. This trip is led by Derek Loeb and is limited to 15 participants.
Bend area participants may meet at Cascade Village Shopping Center, between PetsMart and Ashley Furniture, to ride share or caravan to the trailhead. Please contact Derek Loeb at DerekLoeb@gmail.com with any questions.
Registration must be done via the registration button on the trip listing on the COGS website. Successful registration will be confirmed on the webpage by a light green box indicating registration was successful and by a confirmation email. If you don't get this email you should try the registration process again. If the trip is full, please join the wait list.
Central Oregon Geoscience Society
Email: COGeoSoc@gmail.com P.O. Box 2154, Bend, Oregon 97709
