Cool Science: Younger Dryas Impact Hypothesis

“In summary, evidence has been found in the Pilauco section that is similar to that found at >50 YDB sites on four continents. This is the first time that extensive YDB evidence has been found at high latitudes in the Southern Hemisphere. The evidence reported in this study appears consistent with the proposed effects of a YDB cosmic impact event that affected both the Northern and Southern Hemispheres.”

Scientific Reports, 9, Article number: 4413 (2019)

Malcolm A. LeCompte from Elizabeth City State University and other collaborators used the Hitachi S3200N variable pressure scanning electron microscope (VPSEM) at AIF to get the below images. 

Group 1 SEM Images: High-temperature Fe-rich impact-related spherules. (a–f) High-temperature impact spherules have distinctive dendritic surface texturing indicative of rapid quenching from melt temperatures above ~1450 °C. SEM-EDS analyses for each spherule are in Supplementary Table S7. Elemental composition of spherule in (b) is in Supplementary Fig. S6. (g) Photomicrograph of high-temperature impact-related spherule illustrating the difficulty in distinguishing these from framboids (Fig. 11a) and detrital grains (Fig. 11c). Note percentages of Fe and O at lower right of some images. The composition of these spheroids is FeO (wüstite), a highly reduced mineral that almost never occurs under natural terrestrial conditions, but is common in meteorites and materials produced during impact events under oxygen-deficient conditions.