QUATERNARY GEOLOGY AND LANDSCAPE ECOLOGY IN THE MORES CREEK BASIN, SOUTHWEST IDAHO

Changing abiotic-biotic interactions in the vicinity of Mores Creek, a tributary to the Boise River situated within the boundaries of the Boise National Forest, can be linked to human land use patterns. In addition, human activities in this wildland-urban interface area are directly linked to geologic processes and landscape resources. A prominent geomorphic feature in the lower Mores Creek Valley (LMCV) is the Pleistocene age Mores Creek basalt which overlies Idaho Batholith granitic bedrock and river gravels. Mores Creek has cut through the basalt, exposing the bedrock and alluvial gravels. The top of the flow is exposed along tributary creeks and gulches or is covered with colluvial slope wash as well as alluvium. Away from the canyon, slopes are unstable and subject to landslides. Vegetation patterns are related to elevation, topography, and precipitation. Lower, more arid areas contain sagebrush and grasslands (High Desert eco-region, sagebrush steppe) while higher elevations contain pine and fir forests. The LMCV is an ecotone where, except in riparian settings along drainages or within the canyon, grass and sagebrush (Artemisia sp.) communities typically cover the south facing slopes while ponderosa pine (Pinus ponderosa) and douglas fir (Pseudotsuga menziesii) cover the north facing slopes. The intensity of human use of the LMCV has increased during the late Holocene. Beaver trapping in the region during the early 1800s altered the riparian zones. Starting in the 1860s placer mining, deforestation related to logging, and grazing also modified the landscape. Land-use changes have contributed to changes in hydrology and the increased frequency and intensity of wildland fires. A proposed dam along Mores Creek in the vicinity of Badger Gulch and Rush Creek lies in an area of documented landslides. The dam would inundate several miles along the canyon and effect habitat used by elk (Cervus elaphus) and deer (Odocoileus hemionus). The LMCV is a wildland-urban interface area where human activities are influenced by the geoecologic setting and intensification of human land use has contributed to environmental change.