| NW |
| SE |
|
|
| Columbia River |
|
| Basalt Group lava |
|
| Willamette Silt |
|
|
| Alluvium and coarse- |
|
| grained
basin-fill deposits |
|
|
|
| Marine sediments and |
|
| Western Cascade
rocks |
|
|
|
| Fine-grained
basin- |
|
| fill deposits |
|
|
|
| Gannett & |
|
| Caldwell,
1998 |
|