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We use ground-penetrating radar (GPR) to investigate the geometry, inland extent and continuity of sand layers interpreted as tsunami deposits in the Shetland Islands, UK. Four sites where sand layers within peat deposits have been recorded in previous studies are used to provide ground truth. In addition, we describe survey results from one site where deposits are not exposed to test the potential of GPR to identify candidate tsunami deposits in areas that are not well documented. Sand layers can be clearly imaged at all five locations because they are interbedded with peat and the contrast in lithology gives a good reflection on GPR profiles, even very thin sand layers, <1 cm thick, that are beneath the theoretical resolution of the GPR. 2D and 3D surveys show that tsunami deposits appear to drape a buried topography. Most sand layers form continuous reflections, although some gaps are attributed to later erosion, most likely by streams. Sand layers have been traced up to 150 m inland and 10 m above the present shoreline, which is consistent with data from boreholes. If a similar sized event occurred today, it would have a devastating impact on the Shetland Islands. [ABSTRACT FROM AUTHOR]

Ground penetrating radar (GPR) profiles across a complex linear dune in the Namib Sand Sea have been used to image sets of cross-stratification and their bounding surfaces. A combination of radar facies analysis and radar stratigraphy has been used to interpret the radar profiles and define a relative chronology. Thick sets of cross-stratification indicate when the dune was most active, whereas thin sets of crossstratification are interpreted to indicate the increased prevalence of wind reversals and lower rates of dune migration, with bounding surfaces formed during periods of stabilization, non-deposition or erosion. A drilling and dating campaign was designed on the basis of the dune stratigraphy as defined by the GPR survey. Sampling was targeted at large sets of cross-stratification formed when the dunes were most active, and avoiding bounding surfaces formed when the dune was stable or even eroded. The results from optical dating give ages between 0.34 ± 0.02 ka and 1.57 ± 0.07 ka, indicating a time-averaged dune migration rate of 0.12 m a-1 over the past 1600 years. [ABSTRACT FROM AUTHOR]