UCLA

With an icy exterior covering a global ocean, Europa has long been a target of interest in the search for life beyond Earth. Europa exists in a dynamic environment, subject to intense irradiation and impact as well as immense tides from Jupiter. These processes deliver important thermal and chemical energy that could be critical to supporting a putative biosphere. In the past few decades the debate about habitability of Europa has been focused strongly on the thickness of the ice shell. However, an arguably more critical question is: how does the ice shell recycle? New analysis of Europa’s enigmatic “chaos terrains,” indicates that chaos features form in the presence of a great deal of liquid water, and that large liquid water bodies exist within 3km of Europa’s surface comparable in volume to the Great Lakes. The detection of shallow subsurface “lakes” implies that the ice shell is recycling rapidly and that Europa may be currently active. In this presentation, we will explore environments on Europa and their analogs on Earth, from collapsing Antarctic ice shelves to to subglacial volcanoes in Iceland. I will present these new analyses, and describe how this new perspective informs the debate about Europa’s habitability and future exploration.

The Earth is unique among the terrestrial planets in our solar system in having a fluid envelope that fosters life. The key behind Earth’s habitable climate is well-tuned cycles of carbon (C) and other volatiles. While on ten to thousands of year time-scales the chemistry of fluids in the atmosphere, hydrosphere, and biosphere is dictated by fluxes of carbon between the near surface reservoirs, over million to billion years this is maintained by chemical interactions of carbon between the Earth’s interior, more specifically the Earth’s mantle, and the exosphere. This is because of the fact that the estimated total mass of C in the mantle is greater than that observed in the exosphere and the average residence time of carbon in the mantle is on the ≥1 Ga. But how did the Earth’s mantle attain and maintain the inventory of mantle carbon over geologic time and is the residence time of carbon in the mantle as constrained by the present-day fluxes a true reflection of the carbon ingassing and outgassing rates throughout the history? Also, when in the history of the planet carbon inventory of the mantle got established and how did it change through geologic time? The answers to these questions are important because understanding the origin and chemistry of carbon and how they regulate feedbacks between the planet’s interior and the atmosphere is of fundamental importance owing to far-reaching implications for a number of fields of natural sciences, such as the thermal history of the Earth, internal differentiation, long-term evolution of climate, and origin and evolution of life. Because the abundance and mode of storage of mantle carbon are central to carbon’s role in global geodynamics, it is critical to constrain the processes that modulated the carbon inventory of the Earth’s mantle through time. In this talk, I will try to review ingassing, outgassing, and storage mechanisms of terrestrial carbon, from the time period of early planetary differentiation and magma ocean in the Hadean to the plate tectonic cycles of the modern Earth through Phanerozoic.

The small bodies of the Solar System have a story to tell about the history of our Solar System. Near Earth Objects — asteroids whose orbits bring them near the Earth’s orbit — are interesting both because they sample compositions from throughout the Solar System and because they can, and do, hit the Earth. Kuiper Belt Objects, at the outer edge of the Solar System, are, in contrast, relatively primordial and record the formation environment in the early Solar System. In my talk, I will present our latest results in studies of both Near Earth Objects and Kuiper Belt Objects, focusing on new results obtained with data from the Spitzer Space Telescope, the Hubble Space Telescope, and the STEREO mission.

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.