ANTOINE PEAK CONSERVATION AREA FIELD STUDY: AN UNDERGRADUATE SERVICE-LEARNING RESEARCH PROJECT

Antoine Peak Conservation Area (APCA) is 1,296 acres of mountainous terrain between Forker and Campbell roads north of Spokane Valley. The purpose of this study was to create geologic maps of the area, describe the local bedrock units, and make inferences based on rock textures, fabrics and structures observed in the field.

APCA is structurally within the Spokane dome mylonite zone of the Priest River complex, a metamorphic core complex. Four rock types make up the bedrock geology at APCA: two metamorphic rocks - Newman Lake Gneiss, Hauser Lake Gneiss, and two igneous rocks intruding the metamorphic rocks - Rathdrum Mountain Granite and a light-colored igneous pegmatite. Each rock type shows varying degrees of deformation. The mineral assemblage observed in the Newman Lake Gneiss is quartz, orthoclase, plagioclase, and biotite. The Hauser Lake mineral assemblage consists of quartz, plagioclase, orthoclase, biotite, muscovite, and sillimanite indicating amphibolite facies conditions. Based on visual observations, possible migmatitic Hauser Lake Gneiss in the southern section of APCA is inferred.

Geologic maps were completed indicating contact zones between the Hauser Lake Gneiss and Newman Lake Gneiss. Strike, dip, and lineation measurements were taken. Based on foliations and lineation directions we infer that APCA is located on the western limb of the Spokane Dome within the Priest River complex.

As part of the undergraduate service-learning research project, the full report is available on the Spokane County Conservation Areas website.