Mads Faurschou Knudsen and Peter Riisager, Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK. Pages 71-74.
Based on an observed correlation between the Earth's magnetic dipole moment and oxygen isotope paleo-precipitation records from caves in Oman and southern China, Knudsen and Riisager suggest that the Earth's magnetic field may have influenced the amount of rainfall in low-latitude regions during the past 5000 years. The physical mechanism that underpins the geomagnetic-climate link is provided by the cosmic-ray-climate theory, which suggests that galactic cosmic ray (GCR) particles entering the atmosphere influence the formation of low-altitude clouds and, in turn, climate. The geomagnetic field shields the Earth from GCR particles and, according to the cosmic-ray-climate theory, it therefore has the potential to influence cloud formation, rainfall, and climate. Since the amount of GCR particles entering the atmosphere is also modulated by the Sun, the cosmic-ray-climate theory is central to the ongoing scientific debate regarding the role of the Sun in climate change. Knudsen and Riisager lend support to the notion that variations in the Earth's magnetic field may influence the climate of our planet. They also deliver independent support for certain aspects of the cosmic-ray-climate theory.
Testing the Mojave-Sonora megashear hypothesis: Evidence from Paleoproterozoic igneous rocks and deformed Mesozoic strata in Sonora, Mexico
Jeffrey M. Amato et al., Department of Geological Sciences, New Mexico State University, Las Cruces, New Mexico 88003, USA. Pages 75-78.
In the 1970s, an 800-km-long strike-slip Late Jurassic fault called the "Mojave-Sonora megashear" was postulated to explain the geologic similarities between rocks in the southwest United States and those in northwest Sonora, Mexico. To test this idea, Amat
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