ABSTRACT This one-day field trip of regional geologic significance goes from Spokane, Washington, north along the Pend Oreille River to the Lafarge limestone quarries in the Metaline Formation near Metaline Falls, Washington, USA. Along the way, we will discuss local geologic and geomorphic features, archaeology of the Native culture, features of Pleistocene glaciation and the Eocene Newport fault in the Pend Oreille valley, and highlights of roadcuts and rock types. The main focus of the field trip centers on the paleontology of the lower bedded member of the Metaline Formation in the Lafarge quarry. Based on recent fossil identification of recently discovered trilobites, the age of the lower bedded member has been refined to Series 2-Stage 4 of the Cambrian. We will examine potential new species at stopping points within the quarry, identify key units of stratigraphy and relate them to the stratigraphic column of the guide, and include a structural geology discussion. Deformed trilobites, cleavage, and calcite-filled fractures indicate NW-SE compression during Mesozoic Cordilleran tectonism.

Abstract The first day begins in Spokane and follows Interstate 90 to Missoula, Montana. Stops are at the Rathdrum Prairie ice-dam outburst area east of Spokane; flood out-wash deposits in and around Coeur d’Alene, Idaho; Glacial Lake Missoula deposits west of Missoula, Montana; and Glacial Lake Missoula shorelines that are etched into the hillsides surrounding the city of Missoula. The second day’s travel includes sites in the Missoula Valley that display features associated with the catastrophic emptying of the lake and the subsequent refilling. The remainder of the day’s travel will be north and west of Missoula to sites along U.S. Highway 93 and State Routes 28, 382, and 200 to view the relationship of valley glaciers and Glacial Lake Missoula, pingo scar terrain, large terminal moraines, Joseph T. Pardee’s classic giant current ripple forms and gulch fills in the Camas Prairie and along the Flathead River, and Eddy Narrows, ending in Thompson Falls. The third day’s route continues west on Montana State Route 200 with stops to study glacial gravels associated with ice-dam advances up the Clark Fork River and the features associated with the ice dam that repeatedly occupied the Purcell Trench, dammed the Clark Fork River, and created multiple Glacial Lakes Missoula. Lastly, we will stop at the outburst area in Farragut State Park and the Rathdrum Prairie breakout area to view notable examples of current ripples and outburst features.