The latter depends on the quantity of water flow and stream gradient. The lava may flow during numerous successive or repetitive eruptions and may emanate from single or numerous vents or fissures. Lava of this nature, like basalt, is usually associated with less explosive eruptions; more viscous lavas with lower mafic content, like dacites and rhyolites, can also flow, but tend to be more closely associated with eruptions of greater explosiveness and the formation of pyroclastics.