Old Stone Walls Record History of Earth’s Magnetic Wanderings

By Liza Lester – Re-Blogged From AGU 100

Under the forests of New York and New England, a hidden tracery of tumbledown stone walls marks the boundaries of early American farms, long abandoned for city jobs and less stony pastures in the West.

These monuments of an agrarian past also mark past locations of Earth’s itinerant magnetic north pole, a record leveraged by geochemist and local history buff John Delano to reconstruct a history of our planet’s magnetic field in eastern North America in a new study published in AGU’s Journal of Geophysical Research: Solid Earth.

An old stone wall marks a boundary of a long-abandoned farm near Grafton, New York, once part of the colonial Manor of Rensselaerwyck. A section of the 700,000-acre manor west of the Hudson River was was surveyed for rental allotments in 1787. Credit: John Delano

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