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8. Diorite is the plutonic equivalent of andesite.
9. Andesite never resembles rhyolite, so their identification does not require any
microscopic examination.
10. Gabbro tends to be dark green to black in color and composed primarily of
pyroxene and calcium-rich plagioclase feldspar.
11. In situations where the ash particles remained hot enough to fuse, the rock is
called welded tuff.
12. Pyroclastic rocks composed mainly of particles larger than ash are called
volcanic breccia.

UNIT 16
METAMORPHISM AND METAMORPHIC ROCKS

Task 1. Read and memorize the following words:
pre-existing – існуючий; той, що a parent rock - материнська або корінна
існував раніше порода
elevated - підвищений equilibrium - рівновага
extreme environments – екстремальні high-grade – високометаморфізований,
умови навколишнього середовища високотемпературний
obliterate – знищувати, стирати, large-scale - великомасштабний
викреслювати
fold – складка, вигін temperatures approach – перепад
температури

Task 3. Read the following text, translate it into Ukrainian.

What Is Metamorphism?
Metamorphism is the transformation of one rock type into another. Metamorphic
rocks are produced from pre-existing igneous, sedimentary, or even other metamorphic
rocks. Thus, every metamorphic rock has a parent rock—the rock from which it was
formed. Metamorphism, which means to “change form,” is a process that leads to
changes in the mineral content, texture, and sometimes the chemical composition of
rocks. Metamorphism takes place where pre-existing rock is subjected to new
conditions, usually elevated temperatures and pressures that are significantly different
from those in which it initially formed. In response to these new conditions, the rock
gradually changes until a state of equilibrium with the new environment is achieved.
The intensity of metamorphism can vary substantially from one environment to
another. For example, in low-grade metamorphic environments, the common
sedimentary rock shale becomes the more compact metamorphic rock slate.
In more extreme environments, metamorphism causes a transformation so
complete that the identity of the parent rock cannot be determined. In high-grade
metamorphism, such features as bedding planes, fossils, and vesicles that existed in the
parent rock are obliterated. Further, when rocks deep in the crust (where temperatures
are high) are subjected to directed pressure, the entire mass may deform, producing
large-scale structures, mainly folds.
In the most extreme metamorphic environments, the temperatures approach. The
agents of metamorphism include heat, pressure (stress), and chemically active fluids.
During metamorphism, rocks are usually subjected to all three metamorphic agents
simultaneously. However, the degree of metamorphism and the contribution of each
agent vary greatly from one environment to another.

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