D Question 21 2 pts Lava tubes can form in mafic lava flows because those flows are low viscosity, which enables the lava in the tube to "drain" and leave the hollow tunnel behind. Felsic lava flows are too viscous to enable any "draining", thus tubes won't form in felsic lavas. True O False D Question 22 A volcanic arc is generated by divergence and consists mostly of composite cones. O True O False 2 pts