Geobites: Down-to-Earth summaries of new geoscience research for a broad audience Charles M. Shobe (cshobe@gfz-potsdam.de)1, Kristina T. Vrouwenvelder2, Margaret Moerchen3, and Matthew Giampoala3 1. GFZ German Research Centre for Geosciences, 2. University of Colorado Boulder, 3. American Geophysical Union Site visit statistics: the first month Geobites is supported by AGU. most-viewed post published Twitter promotion by AGU new post published •Visitors are primarily from the U.S. and Europe. •Views are driven almost exclusively by social media promotion. •One problem we face is that only 20% of page views are of science posts; we have a high "bounce rate" from the homepage. Geobites is seeking volunteer writers. Please visit www.geobites.org to get in touch. We currently write in English, but are looking to add Spanish as well. Write for Geobites! Follow us on Twitter @_geobites: Geobites is a new grassroots #scicomm blog where geoscientists write about new research for a broad audience. Geobites is one of a family of "bites" sites, where scientists write about new developments in their field for a non-specialist audience. Geobites has three primary purposes: 1.To keep the interested public–especially undergraduates who might be interested in science careers–up to date with new research, 2.To generate attention for new work that traditional science media outlets might miss, and 3.To allow geoscientists to improve their science writing skills, which will improve communication and trust between scientists and the general public. M A R C H 2 6 , 2 0 2 0 B Y C H A R L I E S H O B E What Caused the Flood that (Possibly)Gave Rise to an Empire? Featured image:The YellowRiver Breaches its Course by Ma Yuan,Public Domain Paper: Uraniumisotopic constraints on the nature of the prehistoricflood at the Lajia site, China Authors: Le Li, Jun Chen,David William Hedding,Yuanhe Fu,Maolin Ye,Gaojun Li A smallsand deposit might holdthe key to dating the rise of Chinaʼsfirst dynasty. Chinese legend holdsthat the leaders who worked to control a giant flood on the Yellow River (knowninChinaas the Great Flood)also foundedthe Xia Dynasty–the first centralizedstate inChinese history– about 4,000 years ago.Proving that the Great Flood actually happened would lend weight to ancient historicalaccounts of the foundingof the dynasty,but the evidence is stillup for debate. Some geologists argue that an earthquake caused the Great Flood.The story goes that the earthquake triggered landslidesthat dammed the Yellow River untilthe dam finally broke,releasing about 16cubic kilometers (four millionOlympic-sizedswimming pools) of water virtuallyallat once. Sediments thought to have been carried downriver by the outburst flood have been found infissures—cracks inthe groundcaused by the earthquake—atan ancient human settlement that the earthquake destroyed.Humanremainsfrom the site have been dated to about 3,900 years old.Proponents of the earthquake-causedGreat Flood theory say that the sediment-filledfissures linkthe earthquake and the flood,thereby givingus the birthdayof the centralizedChinese state. But some of the evidence for the theory that the earthquakeand floodare related is controversial.Opponents argue that the timingof the earthquake (andtherefore the dates on the humanremains)canʼt be directly linkedto the flood because the sands in the earthquake fissures might not be sediments from a giant flood.Instead, they say, the sand might have just washed down from nearby gullies. A new paper now argues that the sand inthe earthquake fissures can be chemically linkedto sources up the Yellow River,providinga strong linkbetween the earthquake and the Great Flood. Le Li and coauthors used a new geochemical techniqueto test whether the sand came from nearby gullies,or from upstream inthe Yellow River.They measured the ratio of two different isotopes of uranium(uranium-234to uranium-238)in the sand;this ratio decreases with the time since the sediments were broke