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1. (2) 2. (3) 3. (2) 4. (4) 5. (1) 6. (2) 7. (4) 8. (3)
Metamorphic Rocks Answers Explained
1. (2) According to the Earth Science Reference Tables (ESRT) page 7, Scheme for
Metamorphic Rock Identification, the Texture can be foliated (top 4 rocks) or nonfoliated
(bottom 4 rocks). Mineral alignment is found in the first three rocks, and the mineral
pyroxene is found in schist and gneiss. Since the question states that the rock does not
have banding it is not Gneiss and must by Schist.
2. (3) Looking at the Rock Cycle chart on page 6 of the ESRT, the type of rock is
determined based on how it formed. Therefore the rocks origin (how it originated).
Igneous rocks form from magma solidifying, sedimentary rocks form from sediments
being cemented together and metamorphic rocks form from heat and pressure.
3. (2) This rock shows a distorted texture. You can tell by the wavy bands of white and
dark minerals. Distorted textures are common in metamorphic rocks which form from
heat and pressure.
4. (4) According to the Earth Science Reference Tables (ESRT) page 7, Scheme for
Metamorphic Rock Identification, the Texture can be foliated (top 4 rocks) or nonfoliated
(bottom 4 rocks). Schist is foliated and Quartzite is not.
5. (1) If a rock is metamorphosed it has undergone heat and pressure. The increase in
pressure compact the rock and makes it more dense.
6. (2) According to the Earth Science Reference Tables (ESRT) page 7, Scheme for
Metamorphic Rock Identification, a rock which forms in a zone of contact metamorphism
is a contact (heat) metamorphic rock. Hornfels is the name of any rock which forms
when rock is altered by heat from a nearby magma or lava.
7. (4) Contact metamorphic rocks form when rock is altered by heat from a nearby
magma or lava. The magma or lava solidifies and turns into igneous rock, the rock the
magma intrudes is usually (always in Earth Science) sedimentary rocks. Therefore
contact metamorphic rocks are found sandwiched between sedimentary rocks and
igneous rocks.
8. (3) Similar to question 3, metamorphic rocks typically are shown with a banded
texture. Choice 1 is inter-grown crystals which is igneous rock, choice 2 is sand
cemented together which is sedimentary rock and choice 3 is pebbles cemented together
which is also a sedimentary rock.