Fig. 2

a Bathymetry of Lake Lauerz. Contour interval of solid lines is 1 m, 0.5 m steps are additionally indicated by dashed lines. Water surface is at 447 m.a.s.l. The course of the modern and ancient Steiner Aa is indicated with bold solid and bold dashed line, respectively. Coring locations are emphasized with crosses. Modified after Lambert and Pfeiffer (1990). bLongitudinal seismic line (vertically exaggerated) along Lake Lauerz with the water surface at the top margin. Ship track is indicated on the bathymetric map above. The division of the lake basin into three subbasins is clearly visible: A shallow northwestern bay, the western basin and the eastern basin comprising the lake’s deepest area (13 m water depth). Retrieved sediment cores are projected onto the seismic line. The three to four reflections following immediately after the first lake floor reflection are caused by the ringing of the transducers and are part of the emitted source signal. Note also the strong multiples indicating an almost complete reflection of the seismic energy at the lake floor. Inset shows a detailed view of the seismic signal in the area of the subaquatic ridge, which is the only spot in the lake basin where the acoustic signal penetrates the subsurface