Preliminary Map Showing Quaternary Geology of the Mooresville East 7.5-Minute Quadrangle, Indiana

The Mooresville East 7.5-minute quadrangle is situated near the maximum limit of Wisconsin Episode glacial deposits in northeastern Morgan County. Till and outwash of Wisconsin Episode age and Holocene alluvium are the dominant surficial materials in the quadrangle. Wisconsin Episode eolian sand, loess, and colluvium are also present, with eolian sand and colluvium being adjacent to the West Fork White River valley and loess blanketing Wisconsin Episode till and outwash. Holocene (post-glacial) alluvium is found in the West Fork White River and White Lick Creek valleys and tributaries. Mississippian Borden Group bedrock controls many aspects of the surficial geology of the southeastern sector of the quadrangle. For much of this area, bedrock controls the topography and is less than 20 ft below the ground surface. It is mantled on the summits and shoulders of interfluves mainly by Wisconsin till and minor amounts of sand and gravel (outwash) and eolian sand. The depth to bedrock (Borden Group) is greater along the trend of the modern West Fork White River valley, with depths greater than 100 ft. This bedrock paleovalley is filled with mainly Wisconsin Episode outwash (sand and gravel), and the paleovalley was a major path for meltwater in central Indiana during the Wisconsin Episode, from around 27,000 to 19,000 years ago. The Wisconsin Episode maximum limit lies just outside the quadrangle boundary to the south and east. The Laurentide Ice Sheet reached its maximum limit 24,000 years ago, based on radiocarbon dating of organics within till at the terminal moraine in the adjacent Cope quadrangle. Evidence for a readvance of the ice sheet is found in the Mooresville East quadrangle, which occurred 21,700 years ago; the southern limit of the readvance runs through the central part of the quadrangle, just south of State Highway 144.

Flow-Mediated Vulnerability of Source Waters to Elevated TDS in an Appalachian River Basin

Widespread salinization—and, in a broader sense, an increase in all total dissolved solids (TDS)—is threatening freshwater ecosystems and the services they provide (e.g., drinking water provision). We used a mixed modeling approach to characterize long-term (2010–2018) spatio-temporal variability in TDS within the Monongahela River basin and used this information to assess the extent and drivers of vulnerability. The West Fork River was predicted to exceed 500 mg/L a total of 133 days. Occurrence and duration (maximum = 28 days) of—and thus vulnerability to—exceedances within the West Fork River were driven by low flows. Projected decreases in mean daily discharge by ≤10 cfs resulted in an additional 34 days exceeding 500 mg/L. Consistently low TDS within the Tygart Valley and Cheat Rivers reduced vulnerability of the receiving Monongahela River to elevated TDS which was neither observed (maximum = 419 mg/L) nor predicted (341 mg/L) to exceed the secondary drinking water standard of 500 mg/L. Potential changes in future land use and/or severity of low-flow conditions could increase vulnerability of the Monongahela River to elevated TDS. Management should include efforts to increase assimilative capacity by identifying and decreasing sources of TDS. Upstream reservoirs could be managed toward low-flow thresholds; however, further study is needed to ensure all authorized reservoir purposes could be maintained.

Anthropogenic strath terrace formation caused by reduced sediment retention

Across North America, human activities have been shown to cause river incision into unconsolidated alluvium. Human-caused erosion through bedrock, however, has only been observed in local and isolated outcrops. Here, we test whether splash-dam logging, which decreased in-stream alluvial cover by removing much of the alluvium-trapping wood, caused basin-wide bedrock river incision in a forested mountain catchment in Washington State. We date incision of the youngest of four strath terraces, using dendrochronology and radiocarbon, to between 1893 CE and 1937 CE in the Middle Fork Teanaway River and 1900 CE and 1970 CE in the West Fork Teanaway River, coincident with timber harvesting and splash damming in the basins. Other potential drivers of river incision lack a recognized mechanism to cause T1 incision or are not synchronous with T1 incision. Hence, the close temporal correspondence suggests that reduced sediment retention triggered by splash damming led to the observed 1.1 mm⋅y−1 to 23 mm⋅y−1 of bedrock river incision and reduction of the active floodplain to 20% and 53% of its preincision extent on the Middle and West Forks, respectively. The development of such anthropogenic bedrock terraces may be an emerging, globally widespread physiographic signature of the Anthropocene.

Timber Losses from West Fork Complex Fire in Southwest Colorado

This article provides an assessment of fire effects on timber burned in the West Fork Complex fire area, located in the San Juan Mountains of Colorado. The West Fork Complex fire burned 109,615 acres in 2013, and suppression costs alone totaled $33.2 million. Much of the fire occurred in spruce–fir forests that were previously affected by spruce beetle (Dendroctonus rufipennis). Several timber sales were actively occurring within the fire footprint, and more were anticipated to begin in subsequent years. To provide a more accurate valuation estimate, base log stumpage data from 2003 through 2017 were included in this study to show high degrees of variation over time. With base log stumpage values determined, estimates of total hundred cubic feet of each significant species were calculated using geospatial and forest inventory analysis data. This study determined the timber value loss resulting from the coupled disturbance events of the spruce beetle epidemic and a wildland fire to be $19,083,102. This estimate will allow for a more accurate valuation of the actual damage resulting from the West Fork Complex fire. This study may also be useful in supporting the literary basis for salvage and fuels management after a beetle outbreak to prevent such timber value losses from occurring.