Aeolian dune dimensions and migration rates are analysed along the Ceará coast, north‐east Brazil. Dunes that are currently mobile along the Ceará coast are composed of barchans and sand sheets. The results show that barchans maintain an equilibrium form, which can be characterized by values of dimensionless shape parameters H/W and W/L, where H is the dune height, W is the wing‐to‐wing width and L is the dune length. Dunes are highly mobile, with average migration rates of 17·5 m year−1 for barchans and 10 m year−1 for sand sheets. The calculated migration rates were found to depend strongly on dune dimensions for both barchans and sand sheets, i.e. the larger the dune is, the lower the migration rate will be. This size dependence was associated with the existence of a representative common transport rate along the dune fields, which induces a different dune migration rate dependent on dune size. Finally, from the observed dune evolution, an aggregated scale aeolian sediment transport was inferred. This bulk transport rate, of the order of 90–100 m3 m−1 year−1, is only valid for a timescale of years to decades, which is the timescale used in dune evolution analysis.

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Coring and acoustic surveying (3·5 kHz) in both rivers and lakes in Central Amazonia provide additional insights into the Late Quaternary hydrological and sedimentological development of the Amazon River and its tributaries. Erosion and accumulation phases were found to be linked to Quaternary sea level changes. The low sea level phase during the last glacial maximum caused deep incision of the Amazon River and erosion in major tributaries such as the Rio Negro, 1500 km upstream from the Amazon mouth. A 3·5-kHz profiling suggests a lowering of the water level by at least 30 m at Manaus. During that phase, the slope of the Amazon valley must have increased, resulting in an increase in bed load transport capacity. The subsequent sea level rise caused a backwater effect far upstream, with silting up of the Amazon valley and the tributary inflows. Former river systems changed into Ria lakes. The floodplains of the Amazon River, the várzea, were formed approximately 5000 years ago when the sea level approached its present-day level

Beach-rock exposures provide a record of Holocene sea-level rise along the 560-km-long northeast-facing coast of Ceará, Brazil, that differs from the record available along the other 4300 km of Brazilian coastline further south. Whereas documentation is available from southern Brazil to show Holocene sea levels as much as 5 m above today's level, our observations along the northeastern coast indicate that sea level here was not above the present-day level during the Holocene. Near Jericoacoara, about 240 km northwest of Fortaleza, characterized by strong surf, Precambrian rocks crop out from under a temporary cover of sand in small protected locations with less surf. Here in this upper tidal zone beach rock is being formed, while it is being dismembered synchronously by erosion at lower tide levels. This shows a rising sea level. Along the entire coast of Ceará west of Ponta Grossa the absence of beach rock higher than spring tide level indicates that sea-level was not above its present-day level during the Holocene.Notches in bedrock situated between 2 m and 6 m above spring-tide high-water level that we formerly described as Holocene, are now believed to be Sangamonian.

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