Volume 1 Issue 3, March 2008

Volume 1 Issue 3

Despite Titan's cold temperatures (about 93.7 K at the equator), fluvial and atmospheric processes are active on this moon of Saturn, with methane playing a similar role to water on Earth. However, Titan lacks a global methane ocean, and rainfall appears to be episodic. The image shows a fish-eye projection of Titan's surface from a distance of about 5 km, taken with the descent imager/spectral radiometer onboard the European Space Agency's Huygens probe, on 14 January 2005. Copyright ESA/NASA/JPL/University of Arizona.

Cover design by Karen Moore

Editorial

  • Editorial |

    International Polar Year is drawing attention to the poles. But if more people are entering this pristine environment as a result, any negative impacts must be justified with commensurate benefits.

Correspondence

Feature

  • Feature |

    International Polar Year 2007–2009 had three predecessors 125, 75 and 50 years ago. These international research efforts were not free from geopolitical interests.

    • Simon Naylor
    • , Martin Siegert
    • , Katrina Dean
    •  & Simone Turchetti

Books and Arts

Research Highlights

News and Views

  • News & Views |

    Numerous long, wall-like ridges can be observed in the Valles Marineris region of Mars. They probably represent fault zones cemented by water-deposited minerals and are indicative of ancient groundwater flow.

    • Jonathan D. A. Clarke
  • News & Views |

    Lakes dammed by ice will commonly spill in catastrophic outbursts. Lake Agassiz-Ojibway, at the margin of the Laurentide ice sheet, burst 8,470 years ago in a subglacial flood whose marks have been scratched into the seafloor of Hudson Bay.

    • Martin Jakobsson
  • News & Views |

    Earthquake data seem to reveal a huge sausage-shaped slab of material detaching itself from the material subducting as two plates meet beneath the Hindu Kush. This largest-ever 'boudin' could tell us more about what happens when continents collide.

    • Linda M. Warren
  • News & Views |

    Deltas are among the most valuable coastal ecosystems, but they are very dynamic and the factors that influence their health are complex. The rate of compaction of underlying sediments might be a more significant factor than was thought.

    • John W. Day
    •  & Liviu Giosan
  • News & Views |

    Whether convection in the Earth's mantle extends through its entire depth or if the mantle is layered has long been debated. Recent research suggests that spatially and temporally intermittent or partial layering is the most likely solution.

    • Paul J. Tackley

Review

  • Review Article |

    Despite Titan's cold temperatures (about 93.7 K at the equator), fluvial and atmospheric processes are active on this moon of Saturn, with methane playing a similar role to water on Earth. However, Titan lacks a global methane ocean, and rainfall appears to be episodic.

    • Jonathan I. Lunine
    •  & Sushil K. Atreya

Letters

  • Letter |

    Eddy activity in the North Atlantic ocean produces fluctuations in ocean-wide volume transport on the order of 20×106 cubic metres per second, on multi-year timescales. Such background noise makes it impossible to detect possible trends in the ocean circulation due to a changing climate without multi-decadal observations in three spatial dimensions.

    • Carl Wunsch
  • Letter |

    Over the last twenty years, changes in the shoreline between the Amazon and Orinoco rivers have largely been controlled by the 18.6 year tidal cycle. By 2015 AD, the tidal cycle will account for 90 metres of shoreline retreat in French Guiana and 6 centimetres of sea level rise.

    • N. Gratiot
    • , E. J. Anthony
    • , A. Gardel
    • , C. Gaucherel
    • , C. Proisy
    •  & J. T. Wells
  • Letter |

    Extensive damage to coastal Louisiana from Hurricane Katrina in 2005 was largely attributed to high rates of relative sea-level rise caused by coastal subsidence. An examination of the underlying Holocene sediments shows that the compaction of peat-rich deposits contributes significantly to Mississippi Delta subsidence rates of up to 5 mm per year.

    • Torbjörn E. Törnqvist
    • , Davin J. Wallace
    • , Joep E. A. Storms
    • , Jakob Wallinga
    • , Remke L. van Dam
    • , Martijn Blaauw
    • , Mayke S. Derksen
    • , Cornelis J. W. Klerks
    • , Camiel Meijneken
    •  & Els M. A. Snijders
  • Letter |

    The Columbia River Basalt Group in the northwestern United States, derived from flood basalt eruptions that occurred 16 million years ago, exhibits variability in geography and trace element geochemistry that has led to a number of proposed magma origins. However, the geochemical variability can be explained by a relatively simple model in which magma is derived from a mantle plume that assimilated continental crust in a centralized magma system.

    • J. A. Wolff
    • , F. C. Ramos
    • , G. L. Hart
    • , J. D. Patterson
    •  & A. D. Brandon
  • Letter |

    Arc-shaped scours, sandwaves and channels on the Hudson Bay seafloor suggest that the catastrophic drainage of lake Agassiz–Ojibway occurred as a subglacial flood beneath the Laurentide Ice Sheet, which covered northern North America.

    • Patrick Lajeunesse
    •  & Guillaume St-Onge

Articles

  • Article |

    Dust input to alpine lakes in the western United States has risen dramatically following westward expansion of human settlements and increased livestock grazing over the past two centuries. The increased dust flux deposits additional nutrients and minerals to the lakes, with important implications for water chemistry, productivity and nutrient cycling.

    • J. C. Neff
    • , A. P. Ballantyne
    • , G. L. Farmer
    • , N. M. Mahowald
    • , J. L. Conroy
    • , C. C. Landry
    • , J. T. Overpeck
    • , T. H. Painter
    • , C. R. Lawrence
    •  & R. L. Reynolds
  • Article |

    A large lens-shaped feature bounded by shear zones characterizes the remnant slab beneath the Hindu Kush region. Rather than dripping by viscous flow, the slab is actively stretching and might eventually break off before descending further into the underlying mantle.

    • Gordon Lister
    • , Brian Kennett
    • , Simon Richards
    •  & Marnie Forster

Erratum

Backstory

  • Backstory |

    Jason Neff and his team searched the depths of frigid alpine lakes for clues on dustiness in the western United States.

  • Backstory |

    Torbjörn Törnqvist and several teams of students ventured into the wilds of the Louisiana coast to investigate Mississippi Delta sediments, armed with only a hand-corer and a fifteen-year-old station wagon.

  • Backstory |

    Patrick Lajeunesse and colleagues enjoyed the picturesque environment of Hudson Bay while mapping its floor in order to understand the nature of the catastrophic outburst flood of Lake Agassiz-Ojibway.