Test yourself

Task 1. Tell whether the sentences are true or false. Correct the false ones.

1. All eruptions are very explosive.

2. There are four primary factors that determine whether a volcano extrudes magma violently or “gently”. They are: the magma’s composition, its temperature, the amount of dissolved gases it contains and lava flows.

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 підсумку	funnel-shaped - воронкоподібний
discharge – виверження	mature – дозріти, цілком розвинутись
terminate - завершувати	path - шлях
circular conduit – круговий трубопровід	pipe – труба, трубкоподібна порожнина

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