2022 “No Moss” field trip: The Enigmatic Ralston Salient

Saturday, July 23, 2022

Trip Leader: Ned Sterne, Consulting Geologist

The Enigmatic Ralston Salient
No Moss Gathering – Colorado Scientific Society Saturday July 23, 2022

Directions:

Meeting Place: Meet at small, unmarked parking lot outside the south fence of the City of Arvada Ralston Water Treatment Plant. From Route 93, turn east on West 66th Ave (Pkwy), makes a U-turn at the entrance to Arvada Reservoir, go back west 225 yards and park in small lot on the north side of the road. If the parking lot is full, park in the lot at the entrance to the Arvada Reservoir and walk back along W. 66th Ave. to the parking lot by the treatment plant. We will hike a 1.4-mile loop to the top of the hill south of W. 66th Ave. (magenta line on index map). Bring walking shoes, water and your favorite snacks.

Stop 2: From the Meeting Place go west on W. 66th Ave and turn south on Rt 93. Go 1.35 miles south on Rt 93 and turn west on W. 56 Ave. Pull immediately into the gravel turnout on the south side of the road. We will do a 0.8-mile hike to the hill south of the road (magenta line on index map).

Description:

Join Ned Sterne for a discussion of the enigmatic Ralston Salient, an element of the Golden fault system. Landslide? Near klippe on a flat thrust sheet? Remnant back thrust wedges in a triangle zone bounded north and south by tear faults?

How did Bill Cobban, Glenn Scott and Richard Van Horn manage to map detail in the Pierre Shale given such poor outcrop? What can Arthur Lakes and the historic coal mines tell us about this structure in the subsurface? What can paleomagnetics tell us about the timing of deformation. What role did the Ralston Dike play in the formation of this feature? Finally, what does the Rocky Flats Alluvium reveal about the history of incision across the Front Range and Denver Basin?
Enjoy!