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Geology of the Pacific Northwest


A six- to eight-page combination background history and lab worksheet is given to students for each field trip. Students answer the lab questions to receive credit for trips taken.

4-Hour Field Trips
Cougar Mountain

STOP 1:  Blakeley Formation – Take I-90 east (toward Spokane). Exit I-90 at exit 13 (Newport Way). Turn right at the bottom of the exit ramp, then take an immediate right onto Newport Way. Drive about 0.5 miles and pull off on the right side of the highway. The Stop 1 outcrop is along the left side of the road. Watch for traffic!

STOP 2:  Renton & Vashon Formations – Continue along Newport Way to the intersection of 164th Ave. SE. Turn left and follow 164th Ave. SE for 1.6 miles before bearing right onto Lakemont Way. Just before crossing Coal Creek, turn left into the Cougar Mountain Wildland Park parking lot. Cross the street and follow the path along the creek to the outcrops.

Seismology Lab and Burke Museum

University of Washington Campus, Seattle

Cle Elum – Taneum Canyon:
Cenozoic Evolution of the Southern Washington Cascades

STOP 1:  Mt. Catherine of the Naches Formation (~40-44 Ma) – Take I-90 east to exit #54 (Hyak) and take a right at the end of the off ramp. Take a second right on Gold Creek Road and stop 0.5 miles down the road, along a large gray cliff on the left side of the road.

STOP 2:  Grande Ronde Formation overlying Ellensburg Formation (~15-20 Ma) – Return to I-90 east. Take Elk Heights Road (Exit 93). Take a left at the end of exit ramp. (Reset odometer to 0.0) Turn right onto Thorp Prairie Road. At 3.8 miles turn right onto Taneum Road. Cross I-90, and bear right along Taneum Road (also called Taneum Canyon Road). At 6.5 miles pull off to the right on shoulder of gravel road at the base of large bedrock cliffs.

STOP 3:  Manastash Formation (~50 Ma) – Continue on Taneum Canyon Road (FR #33) to 9.5 miles. Pull off to the right side of the road.

STOP 4:  Cascade Basement Rocks – Western Washington Terranes (Jurassic-Cretaceous) – Continue on FR #33 (follow signs to Cle Elum). At 12.7 miles stop at intersection of FR #33 and FR #133. Walk about 100 feet up the right fork in the road.

STOP 5:  Peoh Point Overlook – Continue up the right fork of the road. At 15.9 miles bear right at a junction. Continue following the road toward Cle Elum and Peoh Point. At 17.9 miles bear right toward Peoh Point. At 18.5 miles bear left at a four-way intersection, following the signs toward Peoh Point. Lookout points are available at 19.0 miles and 20.0 miles. At 20.0 miles either walk up steep road to observation point or walk the remaining road about 0.5-0.75 miles to old fire tower/weather station (this is Peoh Point).

RETURN TRIP:  Return to intersection with road to Cle Elum (originally at 17.9 miles), now at 22.1 miles. Follow road down to Reservoir Canyon Road at 28.6 miles and take a right. Continue down Reservoir Canyon Road and 4th Street to Cle Elum and return to I-90 west.

Quartz Creek (Snoqualmie Batholith)

STOP 1:  The Western Melange (Jurassic) – Take I-90 to Edgewick Road (exit 34). Take a left at the end of exit ramp. Set your odometer to 0.0 at Ken's Truck Stop. Turn right onto 140th/Middlefork Road. There is a Y where Lake Dorothy Road branches to the right; both of these roads lead to the same place. Eventually these roads will turn into Forest Service (FS) Road #56 (gravel), which winds along the west bank of the Middle Fork of the Snoqualmie River. The first outcrop is on the right at a bend in the river (mile 3.6).

STOP 2:  Contact Aureole A – Continue to Mile Post 5. Outcrop is on the left side of the road (mile 6.0).

STOP 3:  Contact Aureole B – Continue several miles to the next outcrop on the left side of the road (mile 6.6).

STOP 4:  Snoqualmie Batholith (15-18 Ma) – Continue several miles to a large bedrock cliff on the left side of the road. On the right side of the road in the river (mile 9.7).

Discovery Park:
The Glacial History Of Seattle

Take I-90 East to I-5 North. Exit I-5 at Mercer Street (the exit is on the left hand side of the highway). At first traffic light, take a right onto Fairview Ave. Get in the left lane and at the first light take a left onto Valley St. In about 1-2 blocks bear right onto Westlake Ave. Follow Westlake North and under the Aurora Bridge. Continue straight after the bridge, where Westlake will become Nickerson Ave. After about 1 mile, move into the left-hand lane and follow the signs for Emerson Street. After stopping at a three-way stop, turn left and cross over 15th Ave. NW. Turn left onto Emerson Street. Stay in the left-hand lane and follow Emerson to Gilman Avenue. Turn right, following signs, to Fort Lawton. Follow Gilman Avenue to the entrance to Discovery Park. (NOTE: If you are visiting Discovery Park on your own, you cannot park at the beach. You must park at the Visitor Center at the east gate or the parking lot at the south entrance, and walk to the bluff. Hiking maps are available at the Visitor Center.)

STOP 1:  Vashon & Esperance Formations

STOP 2:  Lawton & Olympia Formations

8-Hour Field Trips
Mount Rainier:
Mudflows in Paradise

STOP 1:  Mud Mountain Dam

STOP 2:  Tatoosh Pluton

STOP 3:  Sunrise Overlook

STOP 4:  Mt. Rainier Rocks

STOP 5:  West Cascade Rocks: Ohanapecosh Formation

STOP 6:  Paradise River

STOP 7:  Nisqually Bridge

STOP 8:  Longmire Meadows

STOP 9:  Kautz Creek


Send comments to Rob Viens (e-mail: or call him at his Bellevue Community College office at (425) 564-3158. Office hours are by appointment.

© 2001-2002, Rob Viens, Bellevue Community College. All rights reserved.
Page updated on 5 September 2002  • 
Web development by Jacqueline Engle (URL:, summer 2001