Physical Sciences and Mathematics Commons^™

The Marine Terraces Of Santa Cruz Island, California: Implications For Glacial Isostatic Adjustment Models Of Last-Interglacial Sea-Level History, Daniel R. Muhs, R. Randall Schumann, Lindsey T. Groves, Kathleen R. Simmons, Christopher R. Florian

United States Geological Survey: Staff Publications

Glacial isostatic adjustment (GIA) models hypothesize that along coastal California, last interglacial (LIG, broadly from ~130 to ~115 ka) sea level could have been as high as +11 m to +13 m, relative to present, substantially higher than the commonly estimated elevation of +6 m. Areas with low uplift rates can test whether such models are valid. Marine terraces on Santa Cruz Island have previously been reported to occur at low (<10 m) elevations, but ages of many such localities are not known. Using lidar imagery as a base, marine terraces on Santa Cruz Island were newly mapped, elevations were measured, fossils were collected for U-series dating (corals), strontium isotope compositions and amino acid geochronology (mollusks), and paleozoogeography (all taxa). Sr isotope compositions of mollusks from the highest of three marine terraces give ages of ~2.5 Ma to 1.9 Ma, along with Pliocene ages, fromshells interpreted to be reworked. U-series ages of corals fromthewestern part of the island indicate that low-elevation terraces north of the Santa Cruz Island fault correlate to the LIG. Where corals are lacking, amino acid ratios and faunal aspects support terrace correlation to the LIG high stand of sea. Elevations of most terrace localities north of the east-west trending Santa Cruz Island fault, in both thewestern and eastern parts of the island, range from5.75mto 8mabove sea level, well belowthe modeled paleo-sealevel range. Subsidence is ruled out as a mechanism for explaining the lower-than-modeled elevations, because higher-elevation terraces are present alongmuch of the Santa Cruz Island coast north of the fault, indicating longterm tectonic uplift. The low elevations of the LIG terrace fragments are, however, consistent with a low rate of uplift derived from the higher, ~2.5–1.9 Ma terrace. A number of other localities on the Pacific Coast, also dated to the LIG, have marine terrace elevations below the modeled level. GIA models may have overestimated last interglacial sea level by a substantial amount and need to be revised if used for forecasts for future sea-level rise.

Eolian Sediments, Daniel R. Muhs

United States Geological Survey: Staff Publications

Eolian (windblown) sediments form some of the world’s most dramatic landscapes and comprise important parts of the geologic record. This article reviews the characteristics, origins, and significance of eolian deposits, including windblown sand, silt, and dust.

Landforms composed of eolian sand, either as dunes or sand sheets, occupy substantial areas over the surface of the Earth (perhaps as much as 6% globally, but over ~20% of the world’s arid zones, according to Pye and Tsoar, 2009). Low-latitude arid or semiarid regions, usually under the influence of subtropical high-pressure cells, are some of the largest areas of eolian sand accumulation (Lancaster, …

Reconstruction Of Ancient Microbial Genomes From The Human Gut, M. C. Wibowo, Z. Yang, M. Borry, A. Hubner, K. D. Huang, B. T. Tierney, S. Zimmerman, F. Barajas-Olmos, C. Contreras-Cubas, H. Garcia-Ortiz, A. Martinez-Hernandez, J. M. Luber, K. Reinhard Et Al.

School of Natural Resources: Faculty Publications

No abstract provided.

Challenges Of Brush Management Treatment Effectiveness In Southern Great Plains, United States, Rheinhardt Scholtz, Samuel D. Fuhlendorf, Daniel R. Uden, Brady W. Allred, Matthew O. Jones, David E. Naugle, Dirac Twidwell

School of Natural Resources: Faculty Publications

Woodland expansion is a global challenge documented under varying degrees of disturbance, climate, and land ownership patterns. In North American rangelands, mechanical and chemical brush management practices and prescribed fire are frequently promoted by agencies and used by private landowners to reduce woody plant cover. We assess the distribution of agency-supported cost sharing of brush management (2000−2017) in the southern Great Plains, United States, and evaluate the longevity of treatment application. We test the general expectation that the current brush management paradigm in the southern Great Plains reduces woody plants and conserves rangeland resources at broad scales. This study represents …

The Great Plains Irrigation Experiment (Grainex), Eric Rappin, Rezaul Mahmood, Udaysankar S. Nair, Roger A. Pielke Sr., William Brown, Steven Oncley, Joshua Wurman, Karen Kosiba, Aaron Kaulfus, Chris Phillips, Emilee Lachenmeier, Joseph A. Santanello Jr., Edward Kim, Patricia Lawston-Parker

School of Natural Resources: Faculty Publications

Extensive expansion in irrigated agriculture has taken place over the last half century. Due to increased irrigation and resultant land use land cover change, the central United States has seen a decrease in temperature and changes in precipitation during the second half of 20th century. To investigate the impacts of widespread commencement of irrigation at the beginning of the growing season and continued irrigation throughout the summer on local and regional weather, the Great Plains Irrigation Experiment (GRAINEX) was conducted in the spring and summer of 2018 in southeastern Nebraska. GRAINEX consisted of two, 15-day intensive observation periods. Observational platforms …