SPELEOGENESIS OF MILLERTON CAVE VIA EXPLOITATION OF LOCAL JOINTING WITHIN TONALITE OF BLUE CANYON

Millerton Cave, located in Fresno County California within the Sierra Nevada mountain range, is a stream cut talus roofed cave formed within the Tonalite of Blue Canyon. In previous research, a proposed model of speleogenesis for Millerton Cave was hypothesized based on observations collected from early exploration of the cave's middle and upper sections. A four-step model was created based on those observations, that water in conjunction with sediment eroded out the cave via the exploitation of local joints. To test this, we conducted joint and rock strength surveys within the cave area. Joint surveys and rock strength surveys were conducted in situ of the lower and middle cave sections including multiple above the cave at surface and the surrounding area. Our surveys revealed some joints exposed at the surface follow the trend of the cave, and in situ surveys reveal the direction and the shape of the cave are defined by joints within the Tonalite of Blue Canyon, which is consistent with the hypothesized model.