What do yellowish-brown soils and stone layers tell us about Late Quaternary landscape evolution and soil development in the humid tropics? A field study in the Serra dos Órgãos, Southeast Brazil Udo Nehren a,b, ⁎, André Kirchner b , Jürgen Heinrich b a Technology Arts Sciences TH Köln, Institute for Technology and Resources Management in the Tropics and Subtropics (ITT), Betzdorfer Str. 2, 50679 Köln, Germany b University of Leipzig, Institute of Geography, Johannisallee 19a, 04103 Leipzig, Germany abstract article info Article history: Received 11 April 2015 Received in revised form 24 September 2015 Accepted 25 September 2015 Available online xxxx Keywords: Yellowish-brown soils Stone layers Landscape evolution Pedogenesis Southeast Brazil The occurrence, spatial distribution and properties of yellowish-brown soils and stone layers allow deriving conclusions about landscape evolution and soil development in the humid tropics. In this study, standard soil profiles and saprolite and subsoil samples along an altitudinal gradient from the high mountain ranges (~1500 m.a.s.l.) to the lowlands (~8 m.a.s.l.) in the Serra dos Órgãos mountain range in the Brazilian state of Rio de Janeiro are analyzed. Field mapping techniques and laboratory methods are used to analyze the samples and reconstruct Late Quaternary landscape and soil development processes. It is suggested that the formation of stone layers is polygenetic with dissolution processes (geogenic), bioturbation (pedogenic), and slope processes including coverage of terrace gravels (geomorphic) as possible mechanisms. Yellowing of the upper soil horizons is assumed to be the result of (bio)chemical processes (xanthization, chelation), which took – and take – place in periods of wet climate conditions and closed forest cover in the Late Quaternary. It can be distinguished between pre-colonial and modern yellowish-brown colluvial deposits with or without stone layer(s). It is suggested that the deposition of pre-colonial colluvial soils primarily took place in dryer periods and forest retreat during the Late Pleistocene and Holocene. However, it is proposed that the model of cyclic changes between geomorphic activity with colluviation on the one hand and stability and pedogenesis on the other hand need to be further differentiated due to small-scale temporal and spatial climatic changes and sensitive vegetation responses to these fluctuations. Moreover, it is suggested that due to the very steep relief and intense rainfall in the central mountain ranges of the Serra dos Órgãos, accelerated displacement of soil material by landslides and mudslides took also place under closed forest cover in the late Holocene. Modern colluvial deposits have originated from deforestation and land use intensification processes within the last 300 years. They cover wide parts of the lower slopes, foothills, and depressions and indicate massive erosion and deposition processes since the European colonization. © 2015 Elsevier B.V. All rights reserved. 1. Introduction The evolution and distribution of yellowish-brown soils and stone layers in the humid and semi-humid tropics have been controversially discussed within the last decades. Already Charter (1949) pointed out that soils of the humid tropics of South America and Africa typically consist of three-layered profiles: (1) a fine fraction mantle, (2) a stony layer, and (3) the weathered bedrock. Such soil profiles and single stone layers were described and interpreted particularly in tropical and subtropical environments of South America and Africa, but also in other continents and climatic zones. These works discuss different geological, geomorphological and pedological processes that can be related to stone layer formation in humid to sub-humid tropical landscapes, in particular (a) selective dissolution of bedrock material or dissolution from quartz veins by subsurface flow (Bremer and Späth, 1989; Braucher et al., 2004), (b) residual surface accumulations that were later covered by colluvial, fluvial, or aeolian sediments (Vincent, 1966; Rohdenburg, 1969; Tricart, 1972; Bigarella and Becker, 1975; Stocking, 1978; Semmel and Rohdenburg, 1979; Bibus, 1983; Iriondo and Kröhling, 1997; Lichte and Behling, 1999; Morrás et al., 2009), (c) buried terrace gravels (Bigarella et al., 1965; Rohdenburg, 1982; Veit and Veit, 1985), (d) periodic mass movements, such as soil creep and mudslides (Ruhe, 1959; Tricart, 1972; Moeyersons, 1989), as well as (e) bioturbation and pedoturbation (Nye, 1954; Ollier, 1959; Ruhe, 1959; Moeyersons, 1978; Johnson, 1989; Bremer, 1995; Löffler, 1996; Runge and Lammers, 2001; Bird et al., 2002; Johnson et al., 2005). For Vertisols in the Ethiopian highlands, Moeyersons Catena 137 (2016) 173–190 ⁎ Corresponding author at: Technology Arts Sciences TH Köln, Institute for Technology and Resources Management in the Tropics and Subtropics (ITT), Betzdorfer Str. 2, 50679 Köln, Germany. E-mail address: udo.nehren@th-koeln.de (U. Nehren). http://dx.doi.org/10.1016/j.catena.2015.09.016 0341-8162/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Catena journal homepage: www.elsevier.com/locate/catena