Month: May 2013

Three vignettes of different scales of flow and landscape influence on biotic process will be presented. 1) The Late Precambrian Rangeomorph fauna of Mistaken Point Newfoundland constitute the earliest community of large multicellular organisms. Through flow modeling we demonstrate that these organisms evolved large size to access higher velocities in a low flow environment. Access to velocity overcomes diffusional limits to resource acquisition in a community dependant on dissolved resources, providing the impetus to the evolution of large multicellular form. 2) Rapid landscape evolution of the Society Islands resulted from recent sea-level fall from a mid-Holocene maximum. This fall first generated a plethora of reef-top atolls in Polynesia. In the last two millennia such islands have been eliminated preferentially from the south-sides of the Society Islands as a consequence of wave energy from the Southern Ocean, yielding dramatic change of reef and lagoon environments with attendant consequences for marine life and the human population. 3) Coastal estuaries of California have undergone a maturation process during the Holocene converting many estuaries from bays to lagoonal systems dominated by the episodic/seasonal stream flow of our Mediterranean climate. The impacts of the inter-annual details of stream flow on dispersal of a seasonal-lagoon specialist fish, the tidewater goby, are examined using high-resolution genotyping. Conservation genetic and estuarine restoration issues are touched upon.

Megafloods (terrestrial water flows with discharges exceeding one million cubic meters per second) are the largest known freshwater floods, with flows comparable in scale to (though of shorter duration than) ocean currents. Although there are no modern examples of megafloods, such flows occurred during major periods of Earth’s glaciation and during past epochs on Mars. A prominent example is the paleoflooding caused by late Pleistocene outbursts from Glacial Lake Missoula, which formed when the Purcell Lobe of the Cordilleran Ice Sheet extended south from British Columbia to the basin of modern Pend Oreille Lake in northern Idaho.

This colloquium is intended as an introduction to research on thinking and learning in the Geosciences, pitched for an audience who know a lot about geosciences and not so much about education research. As geoscientists, we ask our brains to make sense of an object larger than the human senses can encompass at one time, older than any time span with which humans have direct experience, which is not susceptible to experimental manipulation, whose crust at any given point has experienced superimposed chemical, physical and biological events, where flows of matter and energy intertwine at a bewildering level of complexity. How do we pull this off? The talk is organized in three concentric rings: The first and broadest ring situates geoscience education research amid physics education research, chemistry education research, drawing on the current National Research Council study on “Discipline-based Education Research.” The middle ring draws from the current Synthesis of Research on Thinking & Learning in the Geosciences project, and explores four key themes: spatial thinking in geosciences, temporal thinking in geosciences, systems thinking in geosciences, and teaching and learning in the field. The most-tightly focused and final section of the talk will dig into one of my own research projects: an effort to understand how geoscientists and geoscience students integrate information from scattered outcrops to form a mental model of a geologic structure.

s the Earth an active fuel cell? Or is it corroding? This talk shows how electrochemical processes on Earth and planets may create a wide range of physical and chemical effects. Experiments and theory suggest that geo-electrochemical processes may generate specific isotope signatures describing electrochemical disequilibrium.

In the southwestern United States and at approximately 40 locations around the world, large sand dunes can generate a loud booming sound during a natural or induced avalanche. The sound builds over time to a single frequency varying from 75 to 105 Hz plus harmonics depending on the dune location and time of the year. This talk will outline the historical references to this phenomenon, as well as our field work involving seismic refraction, ground penetrating radar and sand sampling. In addition, the talk will describe some of our related work on flows of granular materials.

At least five moons of planets in the outer solar system may harbor subsurface liquid water oceans. The total volume of liquid water on these worlds is likely in excess of 100 times the volume of all the liquid water on Earth. These oceans have persisted for much of the history of the solar system and as such they present highly compelling worlds in our search for life beyond Earth. In this presentation Dr. Hand will explain the science behind why we think we know these oceans exist and what we know about the physical and chemical conditions that likely persist on these worlds.

The Sun’s evolving magnetic field causes variations in solar irradiance, heliospheric wind, and geospace conditions that range from seconds-long explosions to billion-year trends. Traces of that variability can be found in Galileo’s drawings and ancient ice sheets, while observations of stars like the Sun provide glimpses of what the Sun did through the ages. This observational material guides us towards an understanding of the root of solar activity – the dynamo – needed to understand the Sun-Earth connections.

Analog field science and exploration research can approximate the Earth’s past as well as humanity’s future in space. Such is the case with the research of the Pavilion Lake Research Project (PLRP). The PLRP, a multi-disciplinary, science and exploration endeavor, focuses on understanding the morphogenesis of modern microbialites in Pavilion Lake, British Columbia, Canada. Over the years, the PLRP has employed a suite of lab and field based methods to accomplish its scientific and exploration goals. The field research demands the seamless integration of science and exploration field activities in an underwater environment inherently hostile to humans. The physical, mental and operational rigors associated with PLRP field science and exploration activities are comparable to extra-vehicular activities (EVA) where scientific exploration is a key driver. These working constraints are not simulated, but real and inextricable from the PLRP’s activities. The PLRPs analog science activities provide a real science setting in which to inform the development of scientific and mission operation architectures, train astronauts as field scientists, test technology, evaluate technical requirements to meet scientific needs, and design science backroom team protocols. Darlene will present a synopsis of the PLRP science and exploration activities with a focus on this past year’s field season at Kelly Lake, BC, Canada.

Planetary oceanography is a developing field of study full of opportunities for discovering and understanding new phenomena that might be observed by future missions. I will describe laboratory measurements of sound velocities in simulated icy world ocean solutions at relevant pressures, temperatures, and compositions, leading to self-consistent thermodynamic data sets. Applications of results from this work constrain the configuration of oceans and ices in Ganymede, and provide new insight into the structure of Europa’s ocean and its interaction with the overlying ice.

On 20 April 2010, while drilling at the Macondo Prospect, situated at the Mississippi Canyon block 252 (MC252), an explosion on the Deepwater Horizon rig caused by a blowout killed 11 crewmen and ignited a fireball visible from 35 miles (56 km) away. Two days later, the rig sank, leaving the well gushing at the seabed and causing the largest offshore oil spill in U.S. history: some 5,000,000 bbl (210,000,000 gal) released into the Gulf of Mexico. The setting of the spill is quite different from other historic marine oil spills that occurred at or near the sea surface. The Deepwater hydrocarbons were released at a depth of ~1,500 m (water pressure ~160 atm) in a high pressure jet (~500 atm), resulting in gas bubbles and liquid oil droplets of different size. Size and chemical composition of the hydrocarbon bubbles and droplets evolved extremely rapidly following release from the well. A complex interplay of physical and biochemical processes determined hydrocarbon-water plume mixing dynamics and affected the composition and spatial distribution of the hydrocarbon mixtures within the water column, at the surface in the resulting oil slick, and in the overlying atmosphere. This presentation considers impact of multiple sources of oil contamination and evaluates the role of different oil weathering processes that change the chemical composition of oil in deep water and their effect on the long-term fate of oil in the Gulf of Mexico coastal waters.