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7. Data of this type led them to examine the possibility that magma might change
(evolve) and thus become the parent to a variety of igneous rocks.
8. It is typically only the magma in the upper part of a magma chamber that has a
sufficiently high gas content to trigger a steam-and-ash explosion.
9. The movement of silica-rich, rhyolitic lava may be too slow to perceive.
10. Andesitic and rhyolitic magmas tend to generate relatively short prominent
flows, a few hundred meters to a few kilometres long.

Task 2. Translate the sentences into Ukrainian paying special attention to
the underlined infinitive complexes. How do we call the underlined complexes?

1. As magma moves up the fractures, a further drop in confining pressure causes
more gas bubbles to form and grow.
2. Hot basaltic magmas contain a smaller gaseous component and permit these gases
to escape with relative ease.
3. On Sunday, May 18, 1980, the largest volcanic eruption to occur in North America
in historic times transformed a picturesque volcano into a decapitated remnant.

Discussion

Task 1. Read and memorize the following words:

intrusive - інтрузивний, плутонічний coarse-grained - крупнозернистий,
грубозернистий
setting- спосіб будови composition - суміш, сплав
mount - накопичення constituent – складова частина, елемент
strip away – знімати, здирати exposure - вихід пластів
contain - містити trace amount of smth. – невелика
кількість, залишки, сліди (чогось)
extrusive – екструзивний (тойб що fine-grained - дрібнозернистий
виступає)
visible - видимий observe - спостерігатись

Task 2. Read the text. Translate it into Ukrainian. Talk about igneous
processes and igneous compositions, provide only general information.

Igneous Processes
Igneous rocks form in two basic settings. Magma may crystallize at depth or
lava may solidify at Earth’s surface. When magma loses its mobility before reaching the
surface it eventually crystallizes to form intrusive igneous rocks. They are also known
as plutonic rocks—after Pluto, the god of the lower world in classical mythology.
Intrusive igneous rocks are coarse-grained and consist of visible mineral crystals. These
rocks are observed at the surface in locations where uplifting and erosion have stripped
away the overlying rocks. Exposures of intrusive igneous rocks occur in many places.
Igneous rocks that form when molten rock solidifies at the surface are classified as
extrusive igneous rocks. They are also called volcanic rocks—after the Roman fire god,
Vulcan. Extrusive igneous rocks form when lava solidifies, in which case they tend to
be fine-grained, or when volcanic debris falls to Earth’s surface.

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