Mass transport events are virtually ubiquitous on the modern continental slope, and are also frequent in the stratigraphic record. They are commonly very large (volumes >10 3 km 3 , areas >10 4 km 2 , thicknesses >10 2 m). They extensively remould sea-floor topography on the continental slope and rise. Turbidity currents are highly sensitive to topography, thus turbidite reservoir distribution and geometry can be significantly affected by subjacent mass transport deposits or their slide scars. Given the abundance of mass transport deposits, we should expect that many turbidite systems are so affected. In fact several well-known deepwater outcrops may represent examples of MTD-influenced sedimentation. Turbidites may be captured within slide scars and on the trailing edges of MTDs. They may also be ponded on and around mass transport deposits, in accommodation developed when the mass movement comes to rest, or subsequently due to compaction or creep. The filling of such accommodation depends on the properties of the turbidity currents, their depositional gradient, and how they interact with basin floor topography. The scale of supra-MTD accommodation is determined largely by dynamics of the initial mass flow and internal structure of the final deposit, and typically has a limited range of length scales. We discuss the implications for reservoir location, geometry and facies distribution, and subsurface identification.

Unique wind ripples attaining heights to 2.3 m, wavelengths to 43 m, and a crest maximum grain size of 19 mm occur on the Argentine Puna Plateau at ~4000 m altitude. These are the largest ripples reported on Earth, comparable only to Mars counterparts. They form in the presence of high proportions of low-density pumice clasts (0.91 g/cm 3 ), although crests are exclusively composed of varnished, normal-density clasts (2.43 g/cm 3 ). Mature ripple profi les are partly excavated on bedrock, so they form by a combination of defl ation, winnowing of fi ner grains, minor wind drift of fi ne gravel, and lagging of clasts >4 cm. The large ripple size appears to be related to strong winds, dense saltation layers, and a long time for evolution. Ripple sizes are smaller on obstacles, as compared to fl at terrain; there is a lack of correlation between clast size, wavelength, and the extreme ripple size (in spite of the thin atmosphere), all of which suggest that while small-scale gravel ripples may form according to a reptation model, their evolution into large-scale types may relate to aero dynamic instabilities originating at the saltation curtain-air interface.

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Erosion of the seafloor is often interpreted to be the result of turbidity currents and reflects their frictional and non-cohesive nature. However, evidence of the interaction between sediment gravity-flows and the substrate forming the sea floor has been increasingly reported in the literature. Based on styles of basal interaction with the substrate, we here propose a broad classification of submarine mass movements labelled free-and no-slip flows. Three mechanisms are proposed for free-slip flows during translation of mass movements that are effectively detached from the substrate; hydroplaning, shear wetting, and substrate liquefaction. In contrast, no-slip flows occur where the mass movement is welded to the substrate, and the strain front lies within the substrate itself. In the latter case, flows can erode by pushing forward and/or ploughing into the substrate, often remobilizing sediments that are later incorporated into the flow, a common characteristic shared by many mass transport deposits (MTDs) containing blocks. Additionally, linear track features (e.g. grooves and striations) are described as a consequence of substrate tooling by rigid blocks. Using outcrops in NW Argentina as a detailed case study, we have recorded evidence for penetration of the strain profile into sediments underlying MTDs and categorised the deformation into no-slip basal deformation that may display continuous and discontinuous profiles. Continuous deformation profiles involve the complete deformation of the uppermost layers of the substrate, while discontinuous deformation profiles preserve a undeformed substrate layer between the MTD and the zone of deformed substrate. These features highlight the erosive and deformational nature of MTDs, and can be used as potential kinematic indicators.