Test yourself

Task: Tell whether the sentences are true or false. Correct the false ones.

1. Texture is an important property because it reveals a great deal about the environment in which the rock formed.

2. Two factors influence the textures of igneous rocks.

3. The rock which has large crystals embedded in a matrix of smaller crystals, is said to have phaneritic texture.

4. Igneous rocks composed of the ejected particles which might be very fine ash, molten blobs, or large angular blocks torn from the walls of the vent during the eruption, are said to have a pyroclastic texture.

5. Rhyolite is a coarse-grained rock composed of about 25 percent quartz and roughly 65 percent feldspar, mostly potassium-and sodium-rich varieties.

6. Granite may be reddish or light gray in color.

7. Many samples of pumice will not float when placed in water.

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 існував раніше	a parent rock - материнська або корінна порода
elevated - підвищений	equilibrium - рівновага
extreme environments – екстремальні умови навколишнього середовища	high-grade – високометаморфізований, високотемпературний
obliterate – знищувати, стирати, викреслювати	large-scale - великомасштабний
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.

Task 4. Answer the following questions, using the vocabulary from Task 1.

1. What are metamorphic rocks produced from?

2. What is a parent rock?

3. What does the word “Metamorphism” mean?

4. Define the term “Metamorphism”.

5. Where does metamorphism take place?

6. Can the intensity of metamorphism vary substantially from one environment to another? If yes, provide an example.

7. When does the common sedimentary rock shale become the more compact metamorphic rock slate?

8. What happens to the intensity of metamorphism in more extreme environments?

9. What happens to the intensity of metamorphism in the most extreme environments?

10. Name the agents of metamorphism. Is the contribution of each agent to the degree of metamorphism the same?

Task 5. Build up 5 types of questions to the 3 underlined sentences from the text.

Task 6. Find English equivalents for the following (see the text). Try to build up your own sentences with them.

Трансформація однієї гірської породи в іншу; зміни у змісті мінеральних речовин; хімічний склад порід; у відповідь на; істотно різнитись від одного середовища до іншого; ідентичність материнської породи; площина напластування; підпадати під дію спрямованого тиску; газові пухирці (у мінералі); тепло; внесок кожного агента.

Task 7. Build up the annotation to the text (in written form).