Jussi Mattila and Eveliina Tammisto of the Geological Survey of Finland investigate the relationships between present-day stresses and bedrock fractures acting as conduits for groundwater at Olkiluoto, Finland. This area is designated as the potential repository for highly active nuclear waste, expected to become operational in 2020. Based on the analysis of a fracture database consisting of 38,703 fracture observations, combined with detailed stress measurements, Mattila and Tammisto conclude that fractures with distinct signs of groundwater flow display patterns that can be attributed to the effect of the present-day stress state and especially to the direction of minimum compression. In addition, based on their analysis, the highest groundwater flows are also associated with fractures having minimum compression perpendicular to the fracture planes. The results of the study are considered to yield important background information for the safety assessment of underground nuclear waste repositories.
The advent of hard-part structural support among the Ediacara biota: Ediacaran harbinger of a Cambrian mode of body construction
Erica C. Clites et al., Glen Canyon National Recreation Area, P.O. Box 1507, Page, Arizona 86040, USA. Published online 28 Feb. 2012; doi: 10.1130/G32828.1.
A team of paleontologists lead by Erica C. Clites of the Glen Canyon National Recreation Area has discovered the oldest animal with a skeleton. Called Coronacollina acula, the organism is between 560 million and 550 million years old, which places it in the Ediacaran period, before the explosion of life and diversification of organisms that took place on Earth in the Cambrian. Coronacollina acula is visualized in the fossils as a depression measuring a few millimeters to two centimeters deep. Notably, it is constructed in the same way that Cambrian sponges were
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Geological Society of America