ABSTRACT Development along the coasts of Oregon and Washington is threatened by a variety of natural hazards, including coastal erosion, landslides, earthquakes, and tsunamis. Property losses have increased significantly in recent years due to past land-use and management practices and an intensification of the physical processes that drive coastal change. This field trip will visit a number of sites that document or illustrate the processes that shape Pacific Northwest coastal geomorphology and create hazards, including potentially catastrophic tsunamis generated by the Cascadia subduction zone. New research documenting ocean processes (including the role of changing wave climates, storm surges, El Nino's, and sea-level rise), tsunamis, and the effects of coastal subduction caused by great earthquakes will be covered. Also examined is the human response, which includes constructing coastal engineering structures, the establishment of coastal “erosion” hazard zones, and various mitigation efforts that are being implemented to prepare for future tsunamis. The field trip concludes on the southern Washington coast at Cape Disappointment State Park adjacent to the Columbia River, where construction of the Columbia River jetties, river flow regulation, and dredging and disposal activities have affected the sediment budget of the Columbia River littoral cell, resulting in changing sediment conditions and management practices for this cell.

One question challenges all disciplines today—how many people with a given standard of living or rate of resource consumption can be sustained in a given area? Geologic factors concerning the natural environment and resources are basic limitations. It is necessary to define legal constraints on land and water use to provide sustained support of man at a specified living standard and technical efficiency. Methods to determine natural geologic limitations to land use, ranging from the community to the regional scale, have been attempted in Oregon. The various geologic factors—such as land stabilities, geohydrology, soil and rock characteristics, landforms, and resources—are defined according to their developmental limitations. Existing land use and trends are then compared to natural limitations to determine conflicting and compatible land uses. Simple systems of presenting and integrating geologic with nongeologic factors are utilized for improved public understanding and participation in the planning process. Final application of geologic factors in land-use planning depends largely on comprehension of them by nongeologists. Even so, a geologist member of the planning team is essential to ensure use of the available geologic data.