photos courtesy of Danielle Declerq, October 2001.

 
Stop 1A:  Grand Ronde lava flow of the Columbia River Basalt Group
at Gingko State Park walking trail, SR 10, west of Vantage.

Stop 1B:  Ellensburg Formation (between Grand Ronde and Wanapum basalt flows)
on the trail.  Note pale color of these interflow sandstones.

Stop 1C:  Trees In Bondage.  Petrified logs in the uppermost Ellensburg Formation.
This is a 15 Ma old elm tree.

 
Stop 1D:  Pillow basalts at the base of the Wanapum, immediately
above the petrified logs.

Stop 1E:  Loess deposits (with bands and veins of caliche) on top of everything.
Probably fairly recent loess, not the 1-2 Ma stuff in the Palouse.

Stop 2.  Roadcut between Stop 1 and Vantage along Highway 10.
Pillow-palagonite complex in basal Wanapum (?): palagonite is orange material.
Overlain by a meter or two of colluvium.

Stop 3A:  Gingko State Park Interpretive Center just north of Vantage, WA.
Looking across the dammed up Columbia River to the subhorizontal basalt flows
on the east side of the river (I-90 on the upper slanting bench on right).
Breaks in slope do not necessarily correspond to flow boundaries!

Stop 3B.  Transplanted basalt columns with petroglyphs at Gingko State Park Interpretive Center.
Locals saved these Native American artifacts from the rising reservoir.  Natives scratched
images into the dark patina (called desert varnish) exposing pale weathered basalt beneath.
 

Stop 4A:  Frenchmen's Coulee, at the Silica Road exit off I-90, not far from the
"Gorge at George".  The Feathers (columns in the Roza Flow, in the Wanapum Group)
is a popular climbing area.

Stop 4B:  Contact between the Roza Flow (above) and the Sand Hollow Flow (below),
interflow sedimentary rocks and soils are found along this contact.  Frenchmen's Coulee.

Stop 4C:  Same contact, showing rubbly aa at top of Sand Hollow flow, and platy
fractures and columns in base of Roza flow.  Frenchmen's Coulee.

Stop 4D:  View west down Frenchmen's Coulee towards hidden Columbia River.
The coulee was carved out by gigantic floods approximately 15-10,000 years ago.
 

Stop 5:  Echo Basin, south of the Feathers (park at Agathla Tower, walk across
top of lava flows).  Echo Basin is another giant coulee.  We're looking straight
down into the basin at the former plunge pool carved out by giant waterfalls.