Wednesday, October 17, 2018

Dessication Cracks In Mars Lake Bed

This Comment and Reply published in the August 2018 issue of Geology is worth reading.

Desiccation cracks provide evidence of lake drying on Mars, Sutton Island member, Murray formation, Gale Crater: COMMENT Brian R. Pratt

Desiccation cracks provide evidence of lake drying on Mars, Sutton Island member, Murray formation, Gale crater: REPLY N. Stein; J.P. Grotzinger; J. Schieber; N. Mangold; B. Hallet; D.Y. Sumner; C. Fedo

The argument concerns the origin of polygonal shaped ridges found on the surface of mudstones deposited in a Martian lake. These millimeter to centimeter high ridges made of sand were interpreted as having formed by sand filling in dessication cracks that form on the surface of a drying lake bed. The alternate view argued is that the sand was injected into cracks formed during seismic events taking place on early Mars.

New about Mars is usually dominated by grand questions about evidence for extraterrestrial life. But scientists inch towards answering such bigger themes by working the nitty gritty. In this case, grit filling up cracks in a mudstone. Such a debate may seem arcane, but understanding these details matter. They form small but essential building blocks of a knowledge base, incrementally adding to the larger picture.

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