Lava low degree of polymerization and high temperature favors chemical diffusion, so it is common to see large, well-formed phenocrysts within mafic lavas. Basalt lavas tend to produce low-profile shield volcanoes or "flood basalt fields", because the fluidal lava flows for long distances from the vent. The thickness of a basalt lava, particularly on a low slope, may be much greater than the thickness of the moving lava flow at any one time, because basalt lavas may "inflate" by supply of lava beneath a solidified crust. Most basalt lavas are of "ʻAʻā" or "pāhoehoe" types, rather than block lavas. Underwater, they
Nisga'a Memorial Lava Bed Provincial Park legend that accounts for the lava as well as geological causes. The park has waterfalls, pools, cinder cones, tree moulds, lava tubes, spatter cones, a lava-dammed lake, caves and other features created by lava flows. The park aims to protect moose, goats, marmots, bears and many other species of wildlife. The park covers 178.93 square kilometres in area. It is believed to be the site of Canada's most recent volcanic eruption and lava flow, a geological disaster that killed an estimated 2,000 people. The source of the eruption was the Tseax Cone. Large lava flows dammed the Nass River and