Question

Original layering in the protolith, shearing, and metamorphic differentiation contribute to what characteristic of gneiss?

1) hardness
2) compositional banding (i.e. alternating light and dark layers)
3) brittle rheology
4) quartz-rich composition
5) resistance to weathering

Answer 1

Gneiss is characterized by alternating light and dark bands of minerals due to original layering in the protolith, shearing, and metamorphic differentiation.

Step-by-step explanation:

Gneiss is a high-grade, foliated metamorphic rock that is characterized by alternating bands or stripes of light and dark minerals. The original layering in the protolith, shearing, and metamorphic differentiation contribute to this compositional banding. The intense metamorphism of gneiss causes minerals to self-segregate into discrete zones, resulting in the distinct light and dark layers. Therefore, the correct answer is 2) compositional banding (i.e., alternating light and dark layers).