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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.
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.
International Polar Year 2007–2009 had three predecessors 125, 75 and 50 years ago. These international research efforts were not free from geopolitical interests.
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.
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.
Long linear ridges in the Valles Marineris region of Mars most likely represent fault zones that have been cemented by water-deposited minerals. This implies that water in the Martian crust could have traversed long distances via faults and fractures.
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.
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.
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.
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.
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.
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.
US geoscience departments are still heavily weighted towards men, especially in the most senior ranks. All scientists, male or female, should work towards a more equal distribution.
