Date:2/26/2013

ts the world over, and form some of the most familiar and spectacular of geological structures. But can you fold an entire mountain belt? Stephen Johnston of the University of Victoria and his colleagues Arlo Weil of Bryn Mawr University and Gabriel Gutierrez-Alonso of the University of Salamanca have been studying the geometry of mountain belts, and their findings, summarized in this review paper, suggest that not only can you bend a mountain belt, but that folds of mountain belts, referred to as oroclines, constitute the largest geological structures on Earth. Based on an extensive compilation of geological and geophysical data, they demonstrate that during the development of a mountain chain, minor bends of faults and folds can develop, but that subsequently the entire mountain chain can be buckled into one or more oroclines. For example, the 320-million-year-old Variscan Mountain chain of Iberia, which formed during the continental collisions that gave rise to Pangea, subsequently buckled giving rise to two coupled oroclines. During buckling, a 2,300-km-long, 300-km-wide, linear mountain chain was shortened by more than 1,100 km, giving rise to two of Earth's largest folds and forming the Iberian Peninsula. These findings suggest that the buckling of mountain chains is an important process responsible for the development and growth of continents.

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Deriving a long paleoseismic record from a shallow-water Holocene basin next to the Alpine fault, New Zealand
K.J. Clark et al., GNS Science, PO Box 30368, Lower Hutt, New Zealand. Posted online 22 Feb. 2013; http://dx.doi.org/10.1130/B30693.1.

Scientists have investigated evidence left by large surface-rupturing earthquakes on the Alpine Fault in New Zealand over an 8,000 year period. The earthquakes left "geological signatures" of alternating peat and silt in the exposed banks of Hokuri Creek, an isolated creek in no
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Contact: Kea Giles kgiles@geosociety.org Geological Society of America Source:Eurekalert

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