Abstract In sedimentary geology, ground penetrating radar (GPR) is used primarily for stratigraphic studies where near-continuous, high-resolution profiles aid in determining: (1) stratigraphic architecture, (2) sand-body geometry, and (3) correlation and quantification of sedimentary structures. In the past, to investigate lateral continuity and variability of sediments, we had to infer the correlation between boreholes, outcrops or shallow trenches. Nowadays, with suitable ground conditions (sediment with high resistivity, e.g. sands and gravels), we can collect GPR profiles that show the subsurface stratigraphy. In addition, 3-D GPR can provide much greater appreciation of sand-body geometry and architecture. GPR is, however, not a universal panacea; in some cases, ground truth is still required because lithological determination is by no means unequivocal, therefore borehole or outcrop data may be required to corroborate the results of a GPR survey. Indeed, the latest GPR survey data, including 3-D depth migration, required both boreholes and outcrop data to generate a 3-D velocity model (e.g. Corbeanu et al. 2001 ). In addition, fine-grained sediments (low resistivity) and areas with saline groundwaters cause rapid attenuation of the radar signal, leading to poor signal penetration. This book begins with an introductory paper ( Jol & Bristow 2003 ) aimed at those with little or no experience of GPR and including the basics of data collection, processing and interpretation. The book is then divided into sections on sedimentary environments, including aeolian and coastal, fluvial and alluvial fan, glacial, and lakes; ancient sediments (reservoir analogues); tectonics; and engineering and environmental applications. The final

Abstract Within sedimentological studies, ground penetrating radar (GPR) is being used with increasing frequency because it yields images of the shallow subsurface that cannot be achieved by any other non-destructive method. The purpose of this paper is to provide an introduction to the collection, processing and interpretation of GPR data so that future sedimentary studies can be improved. With GPR equipment now being lightweight, robust and portable, proper data collection and survey design methods need to be followed in order to acquire high resolution, subsurface digital data. Various factors are discussed including: reflection profiling, velocity soundings, test surveys, topography, logistics, data quality and extreme environments. Basic data processing and visualization are then reviewed, followed by a discussion on GPR interpretation strategies including a background to radar stratigraphy. For the sedimentary geologist or geomorphologist, GPR offers unique data of the shallow subsurface including stratigraphy, geometry, architecture and structure.

Abstract The Maputaland area of northeastern South Africa is characterized by extensive dunefields which developed during polyphase reworking of regional aeolian cover sand from the Mid-Pleistocene to the Holocene. Extended parabolic dunes, many preserved only as wind-rift trailing limbs, as well as areas of sinuous crested dunes, hummocky dune systems and the high, composite, accretionary coastal barrier dune cordon are the dominant dune forms. There are few natural sections exposing the stratigraphic succession and unequivocal relative age relationships between dune systems are uncommon. A ground penetrating radar (GPR) survey of dunes and representative aeolian sand stratigraphic units was undertaken in order to investigate the internal structure of the different dune forms and identify stratigraphic relationships between buried sedimentary units. The GPR profiles revealed that the trailing limbs of almost all the parabolic dunes that were surveyed comprise stacked sand units, separated by low-angle reflections interpreted as bounding surfaces, which accumulated through polyphase vertical accretion. Most extended parabolic dunes are aligned north-south and the upper parts of the dunes are characterized by inclined reflections in GPR profile interpreted as large-scale sets of cross-stratification with apparent dips toward the west. A hummocky dune revealed cross-stratified aeolian sand superimposed on a truncated dune form and probably formed through deflation of pre-existing dunes. Using 100 MHz and 200 MHz antennae, it is clear that GPR is capable of imaging very fine sedimentary structures and buried erosional surfaces in the homogeneous aeolian sand of Maputaland. At some of the sites investigated, the buried sand units identified were sampled by hand-augering for infrared-stimulated luminescence dating. The age determinations on these samples suggest that vertical accretion of up to 7 m of sand occurred intermittently over variable time scales up to 25 000 years on some parabolic dune limbs during the Late Pleistocene. In some complex dunefields, adjacent dunes were mobilized at different times, suggesting that remobilization was localized. The implications of the complex internal structure and vertical accretion of extended parabolic dunes are discussed in the context of changes in vegetation cover and water table due to seasonal and short-term cyclical climate variations as well as long-term climate change patterns during the last glacial cycle and the Holocene.