Major-and trace-element data suggest that some granites exposed in the Sierra Nevada batholith represent appropriate end members in a mixing process that generated voluminous granodiorites. Geochemical trends in a range of rock types indicate that the highest-silica granites have been variably modified by partial melting and/or fractional crystallization. Trends in initial Sr, Nd, and common Pb isotope ratios reveal little variation within a wide range of rock types in the same suite, but significant spatial and isotopic variation among individual suites of rocks. These observations are consistent with the interpretation that granites in the Sierra are generated by partially melting juvenile, mantle-derived diorites and mixed with penecontemporaneous mantle melts. With the exception of one spatially limited suite in this study, there is little evidence that ancient continental crust was involved in the generation of the central Sierra Nevada batholith. Instead, isotopic trends from east to west in this study indicate that the majority of granites in the central Sierra Nevada are likely juvenile crust. These observations may dramatically increase estimates of crustal growth rates in the western United States during the Mesozoic.

Modern geoscience uses equations, models, and numbers in conjunction with observations, maps, and words as fundamental tools for investigating Earth. Yet the U.S. public persists in viewing the study of Earth processes as highly qualitative and, in many states, as a remedial science course that is not accepted as appropriate preparation for admission to U.S. colleges and universities. Geoscience teachers and faculty are working to change this perception by increasing the quantitative content of the geoscience curriculum. From the most mathematical of senior theses to the most basic of introductory courses, geoscience instructors can make these courses more reflective of the full range of tools used in the geosciences by including the quantitative content and methods that pervade geoscience. In addition to being provided with a more realistic perception of our science, college students whose major study is the Earth sciences will be better prepared for geoscience careers and all of our students will be more quantitatively literate.

We present the case for introductory geoscience courses as model venues for increasing the quantitative literacy (QL) of large numbers of the college-educated population. The geosciences provide meaningful context for a number of fundamental mathematical concepts that are revisited several times in a single course. Using some best practices from the mathematics education community surrounding problem solving, calculus reform, pre-college mathematics and five geoscience/math workshops, geoscience and mathematics faculty have identified five pedagogical ideas to increase the QL of the students who populate introductory geoscience courses. These five ideas include techniques such as: place mathematical concepts in context, use multiple representations, use technology appropriately, work in groups, and do multiple-day, in-depth problems that place quantitative skills in multiple contexts. We discuss the pedagogical underpinnings of these five ideas and illustrate some ways that the geosciences represent ideal places to use these techniques. However, the inclusion of QL in introductory courses is often met with resistance at all levels. Faculty who wish to include quantitative content must use creative means to break down barriers of public perception of geoscience as qualitative, administrative worry that enrollments will drop and faculty resistance to change. Novel ways to infuse QL into geoscience classrooms include use of web-based resources, shadow courses, setting clear expectations, and promoting quantitative geoscience to the general public. In order to help faculty increase the QL of geoscience students, a community-built faculty-centered web resource (Teaching Quantitative Skills in the Geosciences) houses multiple examples that implement the five best practices of QL throughout the geoscience curriculum. We direct faculty to three portions of the web resource: Teaching Quantitative Literacy, QL activities, and the 2006 workshop website -Infusing Quantitative Literacy into Introductory Geoscience Courses. These portions of the website are designed to give geoscience faculty the resources they need to infuse quantitative content into their entry-level courses, thereby building the QL of the students who enroll. The infusion of QL in the introductory geoscience classroom allows faculty to realistically represent the quantitative nature of the science to the students who may need it most. Ultimately, the inclusion of pedagogically sound quantitative activities and exercises will serve to increase QL of our educated citizenry.

Using the need for math skills in geoscience courses as an example, Helen E. Burn and Eric M. D. Baer from Highline Community College and Jennifer M. Wenner from the University of Wisconsin Oshkosh make the case for just-in-time embedded remediation to improve student learning while using class time effi ciently.

The Math You Need, When You Need It (TMYN) is a set of online tutorials designed to help students develop and review mathematical skills that are applied in undergraduate geoscience courses. We present results of a three-year study of more than 4000 students in 106 geoscience courses at a variety of post-secondary schools who were assigned TMYN tutorials as supplemental mathematics instruction. Changes in student scores from pre-to post-test suggest that the support provided by programs such as TMYN can begin to reduce the gap between mathematically well-prepared and underprepared students; in essence, TMYN levels the quantitative playing field for all geoscience students. On average, both high-and low-performing students who fully participated in the use of TMYN as a part of their course showed learning gains, although gains were larger for students who performed poorly on the pre-test. Our findings emphasize the conclusion that students who interact with context-specific quantitative problems can potentially improve their mathematical skills, regardless of initial level of mathematical preparation. We suggest that this type of support could generalize to other science courses. KeywordsQuantitative skills, Geoscience, Online mathematics tutorials