Tiny Crystals, Big Story: Time capsules from the Early Mars

Featured Image: Zircon grain under the Scanning Electron Microscope (SEM). Image used with permission from Wikipedia (Emmanuel Roquette).

Article: The internal structure and geodynamics of Mars inferred from a 4.2-Gyr zircon record.

Authors: Maria M. Costa, Ninna K. Jensen, Laura C. Bouvier, James N. Connelly, Takashi Mikouchi, Matthew S. A. Horstwood, Jussi-Petteri Suuronen, Frédéric Moynier, Zhengbin Deng, Arnaud Agranier, Laure A. J. Martin, Tim E. Johnson, Alexander A. Nemchin, and Martin Bizzarro

While sitting in Geology 101 studying the geological time scale, most of us have gone through this experience where we imagined ourselves going back in time; visualizing mammoths passing by, dinosaurs hunting and fighting. But all these pictures start to become hazy and unclear when we reach close to 4 billion years. It is the time for which we have no rock records, and this is where zircons or what I would like to call “tiny survivors” comes in.

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Cave formations show link between ice ages and the tilt of Earth’s axis

Paper: Persistent influence of obliquity on ice age terminations since the Middle Pleistocene transition

Featured image: Stalagmites captured by mareke on Pixabay

Authors: Petra Bajo, Russell N. Drysdale, Jon D. Woodhead, John C. Hellstrom, David Hodell, Patrizia Ferretti, Antje H.L. Voelker, Giovanni Zanchetta, Teresa Rodrigues, Eric Wolff, Jonathan Tyler, Silvia Frisia, Christoph Spötl, Anthony E. Fallick

Our planet has been circling and spinning in a wobbly dance around the Sun for billions of years. The exact motions of this dance- governed by Earth’s near-circular orbit (eccentricity), the tilt of its axis, and the orientation of the tilted axis in space (precession) fluctuate predictably. Variations in this planetary dance have changed the amount and distribution of sunlight reaching Earth’s surface through time, and have determined when the planet experienced long periods of cold temperatures and growth of massive ice caps on the continents (ice ages). However, scientists have not been so sure about which planetary motion is the most important for the timing of ice ages. New research uses climate information stored in caves to precisely link these motions to ice ages, showing that axis tilt may be the most important position in the dance when it comes to pulling Earth’s climate out of those frigid times.  

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