The process looks something like squeezing toothpaste out of a tube, pausing, then squeezing again, and builds up lobes of frozen lava called pillow lavas. Flood Basalts Very hot and fluid basalt which erupts from a long set of cracks in the Earth's surface makes thin flows which can travel long distances. With lots of repeated flows, basaltic lava plateaus like those in eastern Washington and Oregon are formed. Often they build lava domes in the craters of the volcanoes from which they erupt. Bombs Chunks greater than 64 mm in diameter which were liquid when erupted.
Bombs often look like footballs.
The type of lava a volcano erupts controls how the volcano erupts. Also, the minerals in basalt lavas give those lavas a relatively low silica content. Finally, olivine and pyroxene have fairly simple crystal structures. Also, these minerals are framework silicates which have fairly complex crystal structures. With high viscosity, dissolved gas can't escape very easily and can build extreme pressures.