Foram estudadas com o auxilio de fotografias aéreas, nas escala 1:25.000, as características do padrão de drenagem quantitativa e qualitativamente em aéreas de solos desenvolvidas de rochas eruptivas no estado do Paraná. Foram selecionadas bacias hidrográficas de terceira ordem e amostras circulares de 10 Km². As regiões estudadas, assim como as unidades de mapeamento utilizados e as aéreas correspondentes foram as seguintes: região de Jataizinho, Brunizem Avermelhado, 812,5 Km²; região de Formosa D'Oeste, Terra Rocha Estruturada, 780,9 Km²; regiao de Corbélia, Latossolo Roxo, 717,6 Km², todos desenvolvidos de rochas básicas; região de Guarapuava Latossolo Bruno, 520,3 Km² e Terra Bruna Estruturada respectivamente com 131,3 Km², todos desenvolvidos de rochas ácidas. Conclusões: a) os parâmetros: densidade de drenagem, frequência de rios e razão de textura, para amostra circular e bacias foram significativos na separação dos solos; b) amostra circular permitiu a separação do LR distrófico do LR álico e dos BV localizados ao norte e sul do estado, pelos mesmos parâmetros citados; c) existe correlação entre a densidade de drenagem e os índices de intemperismo: morfológico, químico e mineralógico

Aerial photographs were used in a study of drainage network and its quantitative and descriptive characteristics were obtained in areas located in Paraná state, in soils developt from basic and acid rocks. In the aerial photo 1:25.000 scale, were selected by geometric similarity, watersheds of third order ramification and circular sampling with 10 km². The studing region, i ts dimensions and the soils mapping units, were the following: Jataizinho region with 812,5 km² is represented by Reddish Brunizen (BA) or an Argiudoll; Formosa D´Oeste region with 780,9 km² is represented by Terra Roxa Estruturada (TE) or a Rodudalf; Corbélia region represented by "Roxo" Latossol (LR) or an Acrortox with 717,6 km², alI these soils are developed from basic rocks; Guarapuava region represented by Brown Latossol (LB), an Acrohumox, and "Terra Bruna Estruturada" (TB) an Tropohumult with a studied area of 520,3 km² and 131,3 km² respectively, alI developt from acid rocks. The conclusions were the following: a) The parameters of drainage pattern permits to separate the soils developed from basic rocks and soils developed from acid rocks. The drainage density, river frequency and texture ratio, in watersheds and circular sampling were the best index for characterization of soils units; b) With the datas of drainage density river frequency and texture ratio in circular sampling was possible to separate differents inclusions in the studied areas. These parameters were also usefull in the characterization of the soils units designated by dystrophic LR, allic LR and Reddish Brunizen located in North and South of Jataizinho region; c) The parameters: mean length of river differentiate soil mapping units; number of river segments differentiate partially and length of river was not significative; d) The descriptive analysis was useful to help to differentiate the soil units; e) The soils developed from acid rocks, TB and LB have different drainage pattern when compared with similar soils developed from basic rocks, TE and LR, respectively. The drainage pattern of soils designated by TB is similar to BV soils and LB is similar to TE soils and f) There is a close correlation between drainage density and weathering index for soils developed from basic rocks or acid rocks. For basic rocks the weathering sequence going from the less weathered soil (or soiIs with larger value for drainage density) to the most weathered soils (or soils with minor drainage density value) was the following for: basic rocks BA → TE → LR and TB → LB for acid rocks. On this aspect drainage density can be consider a weathering index