«DERRAMES SECUNDÁRIOS» EM BASALTOS

Resumo

During the phase of movement, basalt lava flows can present phenomena of segregation and reabsorption on its tops. Segregation consists in the formation of tongues of lava that can advance over the top of the main flow, resulting in structures named "secondary lava-flows". In some cases, this overlapping may cause collapse of top of primary flows and reabsorption of the material. The mechanism of these phenomena is of great complexity. Secondary flows differ from primary ones only by dimensions and they seem to be a common feature in basalt flows.