Geophysical methods can be used to identify the frequency and spatial distribution of plant debris, as well as for the study of the development of such accumulations in recent depositional settings. Side-scan sonar and a sub-bottom profiler were used to generate acoustic images of plant macroremains along a 16.9 km stretch of the meandering course of the Preto River in the municipality of Itanhaém, São Paulo, Brazil. Numerous inclined heterolithic tratification (IHS) deposits with plant debris constitute point bars, while sand dunes mark the migration of the channel along the straighter portions of the river. A large concentration of methane gas was found associated with older organic sediments in the river. The acoustically generated results were confirmed by the analysis of cores with all data integrated into the geographic information system (GIS) environment. The present study is one of the first to apply the methods of geotechnology to taphonomic research. © SEPM (Society for Sedimentary Geology).265264274Aires Neto, A., Uso da sísmica de reflexão de alta resolução e da sonografia na exploração mineral submarina (2001) Revista Brasileira de Geofísica, 18, pp. 241-255Alexander, J., Fielding, C.R., Jenkins, G., Plant-material deposition the tropical Burdekin River, Australia: Implications for ancient fluvial sediments (1999) Palaeogeography, Palaeoclimatology, Palaeoecology, 153 (1-4), pp. 105-125. , DOI 10.1016/S0031-0182(99)00073-5, PII S0031018299000735Do Amaral, P.G.C., Ledru, M.-P., Branco, F.R., Giannini, P.C.F., Late Holocene development of a mangrove ecosystem in southeastern Brazil (Itanhaém, state of São Paulo) (2006) Palaeogeography, Palaeoclimatology, Palaeoecology, 241 (3-4), pp. 608-620. , DOI 10.1016/j.palaeo.2006.04.010, PII S0031018206002987Bridge, J.S., The interaction between channel geometry, water flow, sediment transport and deposition in braided rivers (1993) Braided rivers, pp. 13-71Burk, D., Uhl, D., Walther, H., Some aspects of the actuotaphonomy of leaves in stagnant ponds with implications for the formation of fossil leaf deposits - Preliminary results (2005) Neues Jahrbuch fur Geologie und Palaontologie - Monatshefte, (12), pp. 705-728Burnham, R.J., Relationships between standing vegetation and leaf litter in a paratropical forest: Implications for paleobotany (1989) Review of Palaeobotany and Palynology, 58, pp. 5-32Burnham, R.J., Paleobotanical implications of drifted seeds and fruits from modern mangrove litter, Twin Cays, Belize (1990) PALAIOS, 5, pp. 364-370Burnham, R.J., Reconstructing richness in the plant fossil record (1993) Palaios, 8 (4), pp. 376-384Burnham, R.J., Patterns in tropical leaf litter and implications for angiosperm Paleobotany (1994) Review of Palaeobotany and Palynology, 81, pp. 99-113Burnham, R.J., An overview of the fossil record of climbers: Bejucos, sogas, trepadoras, lianas, cipó s and vines (2009) Revista Brasileira de Paleontologia, 12, pp. 149-160. , doi:10.4072/rbp.2009.2.05Burnham, R.J., Johnson, K.R., South American palaeobotany and the origins of neotropical rainforests (2004) Philosophical Transactions of the Royal Society B: Biological Sciences, 359 (1450), pp. 1595-1610. , DOI 10.1098/rstb.2004.1531Camargo, A.F.M., Pereira, L.A., Pereira, A.M.M., Ecologia da bacia hidrográ fica do rio Itanhaém (2002) Conceitos de Bacias Hidrográ Ficas: Teorias e Aplicaç ões, pp. 239-256. , Schiaretti, A., and Camargo, A.F.M., eds.,Editora da Universidade Estadual de Santa Cruz (UESC) IlhéusCatanzaro, L.F., Neto, J.A.B., Guimaraes, M.S.D., Silva, C.G., Distinctive sedimentary processes in Guanabara Bay - SE/Brazil, based on the analysis of echo-character (7.0 kHz) (2004) Revista Brasileira de Geofisica, 22 (1), pp. 69-83. , http://www.scielo.br/pdf/rbg/v22n1/a06v22n1.pdfChew, A., Oheim, K., Using GIS to determine the effects of two common taphonomic biases on vertebrate fossil assemblages (2009) PALAIOS, 24, pp. 376-376. , doi: 10.2110/palo.2008.p08-047rChoi, K.S., Dalrymple, R.W., Chun, S.S., Kim, S.-P., Sedimentology of modern, inclined heterolithic stratification (IHS) in the macrotidal Han River delta, Korea (2004) Journal of Sedimentary Research, 74 (5), pp. 677-689Donselaar, M.E., Geel, C.R., Facies architecture of heterolithic tidal deposits: The Holocene Holland tidal basin (2007) Netherlands Journal of Geosciences, 86, pp. 389-402Dorrepaal, E., Cornelissen, J.H.C., Aerts, R., Wallen, B., Van Logtestijn, R.S.P., Are growth forms consistent predictors of leaf litter quality and decomposability across peatlands along a latitudinal gradient? (2005) Journal of Ecology, 93 (4), pp. 817-828. , DOI 10.1111/j.1365-2745.2005.01024.xFalcon-Lang, H., The impact of wildfire on an early carboniferous coastal environment, North Mayo, Ireland (1998) Palaeogeography, Palaeoclimatology, Palaeoecology, 139 (3-4), pp. 121-138. , DOI 10.1016/S0031-0182(97)00142-9, PII S0031018297001429Ferguson, D.K., The origin of leaf-assemblages: New light on an old problem (1985) Review of Palaeobotany and Palynology, 46, pp. 11-188Ferguson, D.K., Plant taphonomy: Ruminations on the past, the present, and the future (2005) Palaios, 20 (5), pp. 418-428. , DOI 10.2110/palo.2005.P05-25pFerrin, A., Duran, R., Dieaz, R., Garcia-Gil, S., Vilas, F., Shallow gas features in the Galician Rías Baixas (NW Spain) (2003) Geo-Marine Letters, 23 (3-4), pp. 207-214. , DOI 10.1007/s00367-003-0158-6Fielding, C.R., Alexander, J., Fossil trees in ancient fluvial channel deposits: Evidence of seasonal and longer-term climatic variability (2001) Palaeogeography, Palaeoclimatology, Palaeoecology, 170 (1-2), pp. 59-80. , DOI 10.1016/S0031-0182(01)00227-9, PII S0031018201002279Frazão, E., Vital, H., Estruturas rasas de gásem sedimentos no estuá rio Potengi (nordeste do Brasil) (2007) Revista Brasileira de Geofísica, 25, pp. 17-26. , doi: 10.1590/S0102-261X2007000500003Fulfaro, V.J., Ponçano, W.L., Ciantelli, C.A., A Planicie de Itanhaém, SP,Atas do 2o Simpó sio Regional de Geologia 1979 (1979) Universidade Estadual Paulista Julio Mesquita Filho, pp. 279-290. , Guaratinguetá , BrazilGastaldo, R.A., The paleobotanical character of log assemblages necessary to differentiate blow-downs resulting from cyclonic winds (1990) PALAIOS, 5, pp. 472-478Gastaldo, R.A., The genesis and sedimentation of phytoclasts with examples from coastal environments (1994) Sedimentation of Organic Particles, pp. 103-127. , Traverse, A. ed.,Cambridge,University Press, Cambridge, UKGastaldo, R.A., The relationship between bedform and log orientation in a paleogene fluvial channel, Weißelster basin, Germany: Implications for the use of coarse woody debris for paleocurrent analysis (2004) Palaios, 19 (6), pp. 587-597Gastaldo, R.A., Douglass, D.P., McCarroll, S.M., Origin, characteristics and provenance of plant macrodetritus in a Holocene crevasse splay, Mobile Delta, Alabama (1987) PALAIOS, 2, pp. 229-240Gastaldo, R.A., Huc, A.-Y., Sediment facies, depositional environments, and distribution of phytoclasts in the Recent Mahakam River delta, Kalimantan, Indonesia (1992) PALAIOS, 7, pp. 547-590Giannini, P.C.F., Guedes, C.F., Nascimento, D.R., Tanaka, A.P.B., Angulo, R.J., Assine, M., Souza, M.C., Sedimentology and morphological evolution of the Ilha Comprida barrier system, southern São Paulo coast (2009) Geology and Geomorphology of Holocene Coastal Barriers of Brazil, pp. 177-224. , Dillenburg, S., and Hesp, P., eds.,Springer, The NetherlandsGiannini, P.C.F., Santos, E.R., Caracterização sedimentológica da lama negra de Peruíbe (SP) (1996) Anais III Congresso Brasileiro de Termalismo 1996, pp. 1-20. , Universidade Federal de Santa Catarina, Santa Catarina, BrazilGingras, M.K., Rasanen, M., Ranzi, A., The significance of bioturbated inclined heterolithic stratification in the southern part of the Miocene solimoes formation, Rio Acre, Amazonia Brazil (2002) Palaios, 17 (6), pp. 591-601Greenwood, D.R., The taphonomy of plant macrofossils (1991) The Processes of Fossilization, pp. 141-169. , Donovan, S., ed.,Columbia,University Press, New YorkGreenwood, D.R., Leaf margin analysis: Taphonomic constraints (2005) Palaios, 20 (5), pp. 498-505. , DOI 10.2110/palo.2004.P04-58Hagen, R.A., Vogt, P.R., Seasonal variability of shallow biogenic gas in Chesapeake Bay (1999) Marine Geology, 158 (1-4), pp. 75-88. , DOI 10.1016/S0025-3227(98)00185-6, PII S0025322798001856Jennings, D.S., Hasiotis, S.T., Taphonomic analysis of a dinosaur feeding site using geographic information systems (GIS), Morrison Formation, Southern Bighorn basin, Wyoming, USA (2006) Palaios, 21 (5), pp. 480-492. , DOI 10.2110/palo.2005.P05-062RJudd, A.G., Hovland, M., The evidence of shallow gas in marine sediments (1992) Continental Shelf Research, 12 (10), pp. 1081-1095Lamparelli, C.C., (1999) Mapeamento Dos Ecossistemas Costeiros Do Estado de São Paulo: Secretaria de Meio Ambiente, p. 108. , coord,CETESB, São PauloMartin-Closas, C., Gomez, B., Plant taphonomy and palaeoecological interpretations. A synthesis (2004) Geobios, 37 (1), pp. 65-88. , DOI 10.1016/j.geobios.2003.01.006Missiaen, T., Murphy, S., Loncke, L., Henriet, J.-P., Very high-resolution seismic mapping of shallow gas in the Belgian coastal zone (2002) Continental Shelf Research, 22 (16), pp. 2291-2301. , DOI 10.1016/S0278-4343(02)00056-0, PII S0278434302000560Orange, D., Garcia-Garcia, A., Lorenson, T., Nittrouer, C., Milligan, T., Miserocchi, S., Langone, L., Trincardi, F., Shallow gas and flood deposition on the Po Delta (2005) Marine Geology, 222-223 (1-4), pp. 159-177. , DOI 10.1016/j.margeo.2005.06.040, PII S0025322705002033Paolo, F.S., Mahiques, M.M., Utilização de métodos acú sticos em estudo de dinâmica costeira: Exemplo na desembocadura lagunar de Cananéia (2008) Revista Brasileira de Geofísica, 26, pp. 211-225. , doi:10.1590/S0102-261X2008000200008Pearson, N.J., Gingras, M.K., An ichnological and sedimentological facies model for muddy point-bar deposits (2006) Journal of Sedimentary Research, 76 (5-6), pp. 771-782. , DOI 10.2110/jsr.2006.070Pessenda, L.C.R., Oliveira, P.E., Mofatto, M., Medeiros, V.B., Garcia, R.J.F., Aravena, R., Bendassoli, J.A., Etchebehere, M.L., The evolution of a tropical rainforest/grassland mosaic in southeastern Brazil since 28 000 14C yr BP based on carbon isotopes and pollen records (2009) Quaternary Research, 71, pp. 437-452. , doi: 10.1016/j.yqres.2009.01.008Rayfield, E.J., Barrett, P.M., McDonnell, R.A., Willis, K.J., A Geographical Information System (GIS) study of Triassic vertebrate biochronology (2005) Geological Magazine, 142 (4), pp. 327-354. , DOI 10.1017/S001675680500083X, PII S001675680500083XRicardi-Branco, F., Branco, F.C., Garcia, R.F., Faria, F.S., Pereira, S.Y., Portugal, R., Pessenda, L.C., Pereira, P.R.B., Features of plant accumulations along the Itanhaém River on the southern coast of the Brazilian state of São Paulo (2009) PALAIOS, 24, pp. 416-424. , doi:10.2110/palo.2008.p08-079rRicardi-Branco, F., Fanton, J.C., Principais registros paleoflorísticos do Cenozó ico brasileiro (2007) Paleontologia: Cenários da Vida, pp. 637-647. , Carvalho, I.S., Cassab, R.C.T., Schwanke C., Carvalho M.A, Fernandes, A.C.S., Rodrigues M.A.C.R., Carvalho, M.S.S., Arai, M., and Oliveira, E.Q.O., eds.,Editora Interciência, Rio de JaneiroScheihing, M., Pfefferkorn, H., The taphonomy of land plants in the Orinoco delta: A model for the incorporation of plant parts in clastic sediments of Late Carboniferous age of Euramerica (1984) Review of Paleobotany and Palynology, 41, pp. 205-240Souza, V.C., Capellari Jr., L., A vegetação de dunas e restingas da Estação Ecoló gica Juréia-Itatins (2004) Estação Estação Ecoló Gica Juréia-Itatins: Ambiente Físico, Flora e Fauna: Holos Editora, pp. 103-114. , Marques, O.A.V., and Duleba, W., eds.,Ribeirão Preto, BrazilSpicer, R.A., The importance of depositional sorting to the biostratigraphy of plant megafossils (1980) Biostratigraphy of Fossil Plants. Successional and Paleoecological Analyses, pp. 171-183. , Dilcher, D.L., and Taylor, T.N., eds.,Dowden, Hutchinson & Ross, Inc., Stroudsburg, PennsylvaniaStaub, J.R., Among, H.L., Gastaldo, R.A., Seasonal sediment transport and deposition in the Rajang River delta, Sarawak, East Malaysia (2000) Sedimentary Geology, 133 (3-4), pp. 249-264. , DOI 10.1016/S0037-0738(00)00042-7, PII S0037073800000427Staub, J.R., Esterle, J.S., Provenance and sediment dispersal in the Rajang River delta/coastal plain system, Sarawak, East Malaysia (1994) Sedimentary Geology, 89, pp. 91-106Steart, D.C., Greenwood, D.R., Boon, P.I., Paleoecological implications of differential biomass and litter production in canopy trees in Australian Nothofagus and Eucalyptus forests (2005) Palaios, 20 (5), pp. 452-462. , DOI 10.2110/palo.2004.P04-57Suguio, K., O papel das variações do nível relativo do mar durante o Quaternário tardio na origem da baixada litorânea de Juréia, SP (2004) Estação Ecológica Juréia-Itatins: Ambiente Físico, Flora e Fauna, pp. 34-41. , Marques, O.A.V., and Duleba, W., eds.,Holos Editora, Ribeirão Preto, BrazilSuguio, K., Martin, L., Formações quaternárias marinhas do litoral paulista e sul fluminense: Boletim Instituto de Geociências Universidade São Paulo (1978) Sociedade Brasileira de Geologia (IG/USP/SBG), pp. 1-55Thomas, R.G., Smith, D.G., Wood, J.M., Visser, J., Calverley-Range, A., Koster, E.H., Inclined heterolithic stratification: Terminology, description, interpretation and significance (1987) Sedimentary Geology, 53, pp. 123-179Weschenfelder, J., Correa, I.C.S., Aliotta, S., Pereira, C.M., De Vasconcellos, V.E.B., Shallow gas accumulation in sediments of the Patos Lagoon, Southern Brazil (2006) Anais da Academia Brasileira de Ciencias, 78 (3), pp. 607-614. , http://www.scielo.br/pdf/aabc/v78n3/17v78n3.pdfWever, Th.F., Abegg, F., Fiedler, H.M., Fechner, G., Stender, I.H., Shallow gas in the muddy sediments of Eckernforde Bay, Germany (1998) Continental Shelf Research, 18 (14-15), pp. 1715-1739. , DOI 10.1016/S0278-4343(98)00055-7, PII S0278434398000557Ybert, J.-P., Bissa, W.M., Catharino, E.L.M., Kutner, M., Environmental and sea-level variations on the southeastern Brazilian coast during the Late Holocene with comments on prehistoric human occupation (2003) Palaeogeography, Palaeoclimatology, Palaeoecology, 189 (1-2), pp. 11-24. , DOI 10.1016/S0031-0182(02)00590-4, PII S0031018202005904