JGE 1996 - Volume 44

Vertical variation in basalt vesicle size and abundance has traditionally been utilized as a relative-age indicator in deformed volcanic terrains. However, there is more to be learned from vesicles than simply which way is up. Recent study of vesicle size-frequency distributions has resulted in quantification of rates of volatile exsolution in pre-eruption magmas, flow motion and cooling processes, as well as the elevation of lava emplacement.

Through analysis of vesicle size-frequency distributions from a series of slabs cut from a single basalt hand-sample, students are introduced to simple rock preparation techniques and subsequent numerical analysis. Additionally, comparison of size-frequencies between sequential slabs allows for introduction of these techniques and the mathematics of bubble growth in fluids.

From our example analysis, it was determined that vertical variation in the size-frequency distribution of basalt vesicles over short distances implies multiple processes of bubble growth. In our sample, bubble enlargement occurred largely through coalescence during buoyant assent. Systematic vertical variation in negative exponential distributions of vesicle sizes indicates that initial coalescence of bubbles is followed by minor inflation and selective combination of only the largest bubbles as lava cools.

The Division of Undergraduate Education (DUE) of the National Science Foundation (NSF) sponsors numerous programs to improve science education at the undergraduate level. Central to this mission are the complementary needs for development of new materials and methods to be used in new or revised courses and curricula, and the development of faculty who can best use these resources to promote effective learning. Two ways of addressing these needs are through the Course and Curriculum Development (CCD) and Undergraduate Faculty and Enhancement (UFE) programs.

Assessment requires (1) measures of results, (2) evaluation of the processes that lead to the results, and (3) a commitment to promote change for the better. Complete assessment employs both summative and formative measures. Summative evaluation is the most common. It takes place at the end of a course, is used for evaluative purposes, and commonly measures student satisfaction. Formative evaluation takesplace while a class is ongoing. It is the indespensible part of assessment that provides a way for us to contiguously monitor our students' learning and diagnose our own teaching practices. Knowledge surveys provide convenient ways to examine changes in students' learning. Data from knowledge surveys have both formative and summative applications. Formative surveys of teachign practices examine process and define a "fingerprint" of the professor's teachign style, which can outline specific areas for improvement. Consultation, in-class videotapes, student management teams, and classroom assessment techniques (CATs) are activities through which one can use formative data to produce real change.

We have developed a new advanced hydrogeology pollutant-transport simulation apparatus that is widely adaptable and can be used for quantitative experiments. It allows students to readily observe processes that are otherwise unobservable because of temporal and spatial constraints and because they take place in the subsurface. The simulator is a gently inclined, 61 cm x 122 cm terrarium with input and outflow ports on either side. The terrarium is filled with layers of sand and clay to simulate stratigraphy. "Wells" are simulated by clear plastic tubes with screened ports that are spaced at regular intervals and depths. In one experiment, water-based dye is injected as a plume in the top center of the terrarium, creating a slug that moves down the gradient towards the wells. Groups of students pipette samples from the wells at regular intervals and qualitatively estimate dye concentrations using a color-tone calibration set. Flow models and time-integrated displays of plume concentrations can be constructed. A second experiment involves measuring water height in the wells and constructing a flow net for the system using a computer program.

Educational technologies are providing exciting new opportunities for instruction in the earth sciences. Whether through networked computer labs, analytical instruments that traditionally have been restricted for use in research labs, or equipment used in the field, these educational technologies have become important instruments of change for the effective teaching and learning of science. Increased access to this type of instrumentation is the key to improved student learning as well as for systemic curricular reform.

The geosciences play a central role in science, mathematics, engineering, and technology education. Earth systems provide accessible and important examples of the applications of principles from the chemical, physical, and life scienes. Earth systems provide the opportunity to develop multidisciplinary thematic approaches that transcend disciplinary boundaries, for example, global cycling, mass ane energy transport, and spatial and temporal relations in natural systems at all scales of observation. Earth systems directly affect the health and safety of our society, particularly with respect to natural hazards and resource utilization. Earth systems are dynamic, heterogeneous, and complex, thus providing excellent possibilites for demonstrating the challenges and opportunities for future scientific investigations. Given the centrality of the geosciences in the overall scientific enterprise, many opportunities naturally arise for geoscientists to enter into partnerships that extend the influence of our science in K-16 education, industry, and as a public service.