Blackwater Draw
The presence of a high number of the hollow magnetic microspherules can be used for identification of the LYDB. Although some scientists failed to find any microspherules at all along the LYDB in the BWD-1 site (Surovell et al. 2009), others reported strongly elevated concentrations of the magnetic microspherules here (Firestone et al. 2007; LeCompte et al. 2012). Our observations confirm those made by Firestone et al. (2007) and LeCompte et al. (2012). In spite of the failure to find microspherules along the LYDB, Surovell et al (2009) reported a number of magnetic microspherules in sediments located above the LYDB (not as a discrete microspherule rich layer though). Such a distribution of the microspherules can be explained by redeposition in younger sediments of the microspherules delivered from along the LYDB. It is appropriate to suggest that Surovell et al. (2009) just failed to sample the microspherule-rich layer because it is visually featureless in the BWD-1 site and is very difficult to identify in the field.
2011 Poster