The Escarpa Devoniana environmental protection area, located in the Meridional Plateau of South Brazil, supports a high diversity mosaic of native araucaria (Araucaria angustifolia) forests and grasslands patches. In order to conduct studies of its dynamics, the biodiversity of grassland-forest ecotones in South Brazil Project team has been developing a methodological approach for sorting ecotonal areas for sampling. This essay validates this methodology to the major grasslands occurrence area in the Brazilian Atlantic Forest Biome, the Campos Gerais region. The entire area was divided into a 1 x 1 km grid that was overlayed with vegetation typology files. The criteria for quadrat selecting were: (a) 25 % or more of forest remnants; (b) 25 % or more of grasslands remnants; (c) at least 20 % of contact between them. The non-supervisioned classification potential ecotonal areas were validated through visual checking in a high resolution qualitative way, always by the same operator. The quadrats could be achieved by the researchers in a *.kmz file, which allows someone selecting them in the Google Earth platform.