The author wishes to thank Peter Barker and Amy Weinheimer for their invitation to work on this material and for their cooperation throughout the study, Andreas Zingler for sample preparation and generating the coarse-fraction data, and Kjell Bjørklund for a constructive review of the initial manuscript. This work was supported by DFG ODP Schwerpunktprogramm grants LA 1191/1-1 and 1191/1-2.