Fig. 40. Grade and facies describe metamorphism

Many of the metamorphic rocks consist of flaky materials such as mica and chlorite. These minerals cause the rock to split into thin sheets and rocks become foliated. Slate, schist and gneiss belong to the group of foliated metamorphic rocks. Marble and quartzite are non-foliated metamorphic rocks.

The structure of metamorphic rocks is of importance because it shows the nature of pre-existing rocks and the mechanism of metamorphic deformation. Every trace of original structure is of great importance to geologists. It gives an opportunity of analyzing the causes of its metamorphism. Metamorphic rocks represent the oldest portion of the Earth’s crust. They are mostly found in the regions of mountain belts where great dislocations on the Earth took place.

(М.Я. Баракова, Р. И. Журавлева, Английский язык для горных инженеров, М. 2001)

Table 6. Classification of Common Metamorphic Rocks

EXERCISES

Define the following terms with their similar meaning in Russian

metamorphic rocks; some changes in texture; in mineral composition; the description of metamorphism; schistose structure; the role of water; four variable geologically related parameters; flaky materials; the mechanismof metamorphic deformation; crystallineschists; the great dislocation of the Earth’s crust; during normal progressive metamorphism.

2.2 Match the English equivalents to the Russian terms.

2.3 Match the Russian equivalents to the English terms.

Fill in the gaps using the word formations.

1. Metamorphic rocks which have a schistose structure can___________.

2. As a result of splitting _________________ is formed.

3. Generally speaking, the constituents of gneiss are distributed in bands or layers and the rock ______________ easily.

1. The _____________ between rock pressure and temperature is interdependent.

2. The role of water in metamorphism can be characterized at least by four variable geologically ____________ parameters.

3. These parameters _______________ to each other.

1. A rock ___________ when it splits into thin sheets.

2. Marble and quartzite are non-_____________ metamorphic rocks.

3. ______________ is a characteristic feature of only metamorphic rocks.

1. Gneiss, marble and slate _____________ from granite due to their schistose structure.

2. There are many _________________ types of metamorphic rocks due to two main factors.

3. The _____________ between low-grade and medium-grade metamorphic rocks is the amount of water present.

Match the similar word in column A to the one in column B

Match the opposite word in column A to the one in column B