GRADUATE STUDENTS
Amanda Erling (graduated 2021): Depositional history and stratigraphic correlation of facies of the Tuscan Formation along Highway 32, Chico, CA
Excellent exposures occur in the foothills just east of the city of Chico, CA. Amanda's research involved characterizing Tuscan deposits along the Highway 32 Ridge of Upper Bidwell Park and the Big Chico Creek Ecological Reserve (BCCER). She built on work from a recently completed Masters project conducted across the canyon along Musty Buck Ridge (Gonzalez, 2014). Her work acknowledged that the previous stratigraphic nomenclature of Tuscan Formation (Members A, B, C, D) were inadequate to properly characterize the Tuscan deposits. Instead, Amanda's approach mirrored the work of Gonzalez (2014) by mapping the boundaries between the different flow types of the Tuscan lahar deposits as well as relative time correlative surfaces in 3-D exposures where available. By mapping these surfaces, conclusions can be made about whether the original Tuscan flows occurred in a confined or unconfined environment as well as the down flow and lateral continuity of these deposits.
This field work also included aerial drone photography so that the stratigraphic columns could be calibrated and utilized in inaccessible areas such as cliff exposures. By utilizing a computer program called Agisoft PhotoScan, these drone photos have the potential to generate high resolution digital elevation models of the outcrops which were used, along with a GPS, to map the contacts more precisely.
Overall, Amanda's work on the Tuscan, though focused in the outcrops, also provided predictions on the subsurface extent of various depositional facies. These predictions can then assist groundwater models by representing the stratigraphy the aquifer more accurately. In a time of drought when water users lean more heavily on groundwater pumping, refining groundwater models will only help those protecting and managing this invaluable resource for northern California.
This field work also included aerial drone photography so that the stratigraphic columns could be calibrated and utilized in inaccessible areas such as cliff exposures. By utilizing a computer program called Agisoft PhotoScan, these drone photos have the potential to generate high resolution digital elevation models of the outcrops which were used, along with a GPS, to map the contacts more precisely.
Overall, Amanda's work on the Tuscan, though focused in the outcrops, also provided predictions on the subsurface extent of various depositional facies. These predictions can then assist groundwater models by representing the stratigraphy the aquifer more accurately. In a time of drought when water users lean more heavily on groundwater pumping, refining groundwater models will only help those protecting and managing this invaluable resource for northern California.
Glenn Hoffmann (graduated 2021): Geologic mapping of the Tuscan Formation and related rocks within the 7.5' Richardson Springs Quadrangle, Butte County, California
Funded through a USGS EDMAP program, this project covered the northeast quadrant of the 7.5’ Richardson Springs Quadrangle approximately 10 km north of Chico due to ease of access, excellent exposure, and connection to previously studied outcrops. Glenn tested a recently developed mapping methodology using time-correlative surfaces that separate groups of facies associations into mappable stratigraphic packages which highlights thickness trends, stratigraphic pinch-outs, and a higher resolution depositional history. Glenn created a geologic map (1:12,000) and stratigraphic panels using traditional mapping skills, measured sections, facies characterizations, as well as drone photography and photogrammetry software. He also sampled material for tephrachronology to better define a lower age limit for the Tuscan.
Evan Davis (on-going): Modeling the Lower Tuscan Aquifer (Pliocene) in the northern Sacramento Valley, CA
The hydrostratagraphic relationship of the Lower Tuscan Aquifer (LTA) within the framework of the overlying upper Tuscan Formation, the underlying Upper Princeton Valley and Ione formations as well as the interfingering of the Tehama Formation to the west has yet to be fully developed. In addition, the LTA has not been studied to the extent necessary to determine its sustainability and safe yield. This study will produce a focused 3-D geologically-based static model of the LTA that uses all of the available data designed to assist with answering the following questions:
1. Are current conceptual depositional models for the lower Tuscan Formation consistent with hydrogeologic constraints determined from recent pump-tests?
2. Do regional models accurately reflect localized aquifer heterogeneity and can they be relied upon to reflect impacts from increased pumping in comparison with a higher resolution 3-D geologically-based model of a focused study area?
Existing conceptual models suggest an interfingering of the Coast Ranges-sourced Tehama Formation derived from the west and the Cascades-sourced sands of the Tuscan Formation derived from the east within the center of the northern Sacramento Valley. An alternate interpretation indicates more distinct boundaries between three depositional systems (Greene & Hoover, 2014). This study will test the hydraulic connectivity between the depositional systems.
1. Are current conceptual depositional models for the lower Tuscan Formation consistent with hydrogeologic constraints determined from recent pump-tests?
2. Do regional models accurately reflect localized aquifer heterogeneity and can they be relied upon to reflect impacts from increased pumping in comparison with a higher resolution 3-D geologically-based model of a focused study area?
Existing conceptual models suggest an interfingering of the Coast Ranges-sourced Tehama Formation derived from the west and the Cascades-sourced sands of the Tuscan Formation derived from the east within the center of the northern Sacramento Valley. An alternate interpretation indicates more distinct boundaries between three depositional systems (Greene & Hoover, 2014). This study will test the hydraulic connectivity between the depositional systems.