Event layer: tephra layer - the Laacher See tephra, ca. 12,880 varve years BP

Basal part of the Laacher See tephra (LST) layer (upper third of the image) in the sediment record of Sacrower See, NE Germany. The tephra layer has been dated to 12,880 varve years BP in sediments of Meerfelder Maar, Eifel, Germany (Brauer et al., 1999).The tephra layer mainly consists of volcanic glas with gas vesicules. The condenser aperture of the microscope has been closed to increase the contrast between the glas particles and the embedding resin which have a similar refractive index. A close-up of a tephra particle can be found at doi:10.1594/PANGAEA.778778.left: normal light, 200x magnification; right: polarized light, 200x magnification