Four main geological formations from the state of Rio Grande do Sul, Southern Brazil. The study area (Quaternary deposits) as well as previous studies used in Dice Similarity Index analysis is entirely inserted in Coastal Plain. Key: 1 present study 2 Turuçu River basin; Burns et al. 2015 3 Corrientes Stream; Volcan et al. 2012 4 Tapes Butiazais; Becker et al. 2007 5 Fortaleza lagoon; Schifino et al. 2004 6 Lagoa do Peixe; Loebmann and Vieira 2005 7 Peat forest; Quintela et al. 2007 8 Rio Grande coastal streams; Tagliani 1995 9 Cassino coastal streams; Bastos et al. 2013 10 Taim wetland; Garcia et al. 2006 11 Lagoa Mangueira; Artioli et al. 2009.