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3. The mobility of lava is strongly influenced by temperature.
4. A magma’s viscosity is directly related to its silica content.
5. The amount of volatiles contained in magma never affects its mobility.
6. As the magma body cools, minerals having high melting temperatures crystallize
first.
7. Only some magmas contain some water and other volatiles.
8. Lava fountains are always spectacular and mostly harmless and not generally
associated with major explosive events that cause great loss of life and property.
9. Volcanic explosions can continue until the entire magma chamber is emptied.
10. The vast majority of lava on Earth is basaltic in composition.
11. AA flows exhibit smooth surfaces that often resemble the twisted braids of ropes.
12. Aa and pahoehoe lavas can erupt from the same vent.
13. Pillow lavas are useful in the reconstruction of geologic history.

Task 2. Choose the correct variant in the summary below:
The primary factors that determine the nature of volcanic eruptions include the
magma’s composition/chaines, its pressure/temperature, and the amount of dissolved
gases/fat it contains. As lava cools, it begins to congeal and, as freezing/viscosity
increases, its mobility decreases. The viscosity of magma is also directly related to its
silica/ halide content. Basaltic/Rhyolitic lava, with its high silica content (over 70
percent), is very viscous and forms short, thick flows. Basaltic/ Rhyolitic lava, with a
lower silica content (about 50%), is more fluid and may travel a long distance before
congealing. Dissolved gases tend to make magma less/more fluid and, as they expand,
provide the force that propels molten rock from the volcano.

UNIT 7
VOLCANIC STRUCTURES AND ERUPTIVE STYLES
Part 1

Task 1. Read and memorize the following words:
gradual – поступовий, послідовний accumulation – скупчення, маса
erode – розмивати, піддаватися ерозії collapse – рушитись, розвалитись
rim – край кратера depression - улоговина, низина,
западина,
in rare cases – у рідких випадках exceed – перевищувати, бути більшим
flank – бік, сторона fumarole – випаровування, суфляр
eventually – врешті-решт, у кінцевому funnel-shaped - воронкоподібний
підсумку
discharge – виверження mature – дозріти, цілком розвинутись
terminate - завершувати path - шлях
circular conduit – круговий pipe – труба, трубкоподібна
трубопровід порожнина

Task 2. Read the following text, translate it into Ukrainian.

Anatomy of a Volcano
Volcanic activity begins when a fissure (crack) develops in the crust as magma
moves forcefully toward the surface. As the gas-rich magma moves up through a
fissure, its path is usually localized into a circular conduit, or pipe, that terminates at a
surface opening called a vent. Successive eruptions of lava, pyroclastic material, or a

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