http://SaturnianCosmology.Org/ mirrored file For complete access to all the files of this collection see http://SaturnianCosmology.org/search.php ========================================================== Nanodiamonds in the Younger Dryas Boundary Sediment Layer D. J. Kennett,^1^* J. P. Kennett,^2 A. West,^3 C. Mercer,^4 S. S. Que Hee,^5 L. Bement,^6 T. E. Bunch,^7 M. Sellers,^7 W. S. Wolbach^8 We report abundant nanodiamonds in sediments dating to 12.9^ ± 0.1 thousand calendar years before the present at multiple^ locations across North America. Selected area electron diffraction^ patterns reveal two diamond allotropes in this boundary layer^ but not above or below that interval. Cubic diamonds form under^ high temperature-pressure regimes, and n-diamonds also require^ extraordinary conditions, well outside the range of Earth's^ typical surficial processes but common to cosmic impacts. N-diamond^ concentrations range from {asymp} 10 to 3700 parts per billion by weight,^ comparable to amounts found in known impact layers. These diamonds^ provide strong evidence for Earth's collision with a rare swarm^ of carbonaceous chondrites or comets at the onset of the Younger^ Dryas cool interval, producing multiple airbursts and possible^ surface impacts, with severe repercussions for plants, animals,^ and humans in North America.^ 2009