16. Several kilometers from a volcano, a geologist observes old lava flows made up of dark-colored basalt rock.
What element is the most abundant in themagma within the earth's crust?
A. Aluminum
B. Iron
C. Oxygen
D. Silicon
17. Viscosity refers to the material's resistance to flow. How will you describe the viscosity of magma if a
volcanoundergoes a quiet eruption?
A. more viscous
B. less viscous
C. cannot be determined D. both A and B​