Analyses of pelagic limestones indicate that the flux of extraterrestrial helium-3 to Earth was increased for a 2.5-million year (My) period in the late Eocene. The enhancement began ~1 My before and ended ~1.5 My after the major impact events that produced the large Popigai and Chesapeake Bay craters ~36 million years ago. The correlation between increased concentrations of helium-3, a tracer of fine-grained interplanetary dust, and large impacts indicates that the abundance of Earth-crossing objects and dustiness in the inner solar system were simultaneously but only briefly enhanced. These observations provide evidence for a comet shower triggered by an impulsive perturbation of the Oort cloud.
CITATION STYLE
Farley, K. A., Moǹtanari, A., Shoemaker, E. M., & Shoemaker, C. S. (1998). Geochemical evidence for a comet shower in the late Eocene. Science, 280(5367), 1250–1253. https://doi.org/10.1126/science.280.5367.1250
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