Geology

Recording the Doldrums

See allHide authors and affiliations

Science  14 Dec 2012:
Vol. 338, Issue 6113, pp. 1397
DOI: 10.1126/science.338.6113.1397-c

The winds in the “doldrums” region near the equator are rather calm, and marine settings there see barely any hurricanes. The relative stability of ocean currents and waves in this region minimizes disruption of seafloor sediments and benthic communities. This is likely to have been true at other points in Earth history as well, such as the Late Ordovician, when there were also polar regions with permanent ice caps. To search for clues of a hurricane-free equator in the geologic record, Jin et al. examined a 6000-km cross section across the margins of what was then the continent of Laurentia—containing modern-day North America, Greenland, and northern Europe. Massive carbonate deposits containing abundant Thalassinoides trace fossils and persistent brachiopod shell beds suggest environments in which shallow water with relatively few major hurricanes would host and/or preserve these fauna. The belt corresponds remarkably well to the equatorial region in paleomagnetism-based plate reconstruction models of the Late Ordovician, providing independent validation of such models.

CREDIT: JISUO JIN

Geology 10.1130/G33688.1 (2012).

Navigate This Article