Test yourself

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

1. Calderas are large depressions with diameters that exceed 1 km and have a somewhat triangular form.

2. Most calderas are formed by the collapse of the summit of a large composite volcano following an explosive eruption of silica-rich pumice and ash fragments.

3. The greatest volume of volcanic material is extruded from fractures in the crust called fissures.

4. A dome-shaped mass is called a lava dome.

5. One rare type of pipe is called a diatreme.

6. Cinder cones are not easily eroded.

7. Basaltic shields that emit very fluid lavas comprise most of the islands of the deep ocean basins.

8. Volcanic structures that appear to be somewhat randomly distributed in the interiors of the continents are usually found in Australia.

9. Decompression melting is the most common process by which mantle rocks melt.

10. Geologists have determined that the mantle beneath hot spots must be 100 to 150 °C hotter than normal mantle material.

Task 2. Choose the best variant:

Most passive / active volcanoes are associated with plate / continental boundaries. Active areas of volcanism are found along mid-ocean ridges where seafloor spreading is occurring (convergent / divergent plate boundaries), in the vicinity of ocean trenches where one plate is being subducted beneath another (convergent/ divergent plate boundaries), and in the interiors of plates themselves (convergent plate volcanism / intraplate volcanism / divergent plate volcanism). Rising plumes of hot mantle rock are the source of most intraplate volcanism.

UNIT 9

EARTH’S EXTERNAL PROCESSES

PART 1

WEATHERING AND SOIL

Task 1. Read and memorize the following words:

alteration – зміна, перебудова, деформація	disintegration – розпад, руйнування
mass wasting – зсув, оповзень	elevate – підвищувати, розвивати
derive – отримувати, діставати	elevation – висота, височина
іn response – у відповідь	gradually – поступово, помалу
accomplish - виконуватись	involve - залучати
underestimate - недооцінювати	power – живитись енергією, підтримуватись
external – зовнішній (екзогенний)	stream – річка, струмок
overlie - лежати (над чим-небудь, на чому-небудь)	subtle – ледве помітний
removal – видалення, ліквідація	pore space – порожнина пор

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

Weathering and Soil

Weathering, mass wasting, and erosion are called external processes because they occur at or near Earth’s surface and are powered by energy from the Sun. External processes are a basic part of the rock cycle because they are responsible for transforming solid rock into sediment. 200 years ago, most people believed that mountains, lakes, and deserts were permanent features of an Earth that was thought to be no more than a few thousand years old. Today we know that Earth is 4.6 billion years old and that mountains eventually succumb to weathering and erosion, lakes fill with sediment or are drained by streams, and deserts come and go with changes in climate.

Earth is a dynamic body. Some parts of Earth’s surface are gradually elevated by mountain building and volcanic activity. These internal processes derive their energy from Earth’s interior. Meanwhile, opposing external processes are continually breaking rock apart and moving the debris to lower elevations. The latter processes include:

1. Weathering—the physical breakdown (disintegration) and chemical alteration (decomposition) of rocks at or near Earth’s surface.

2. Mass wasting—the transfer of rock and soil downslope under the influence of gravity.

3. Erosion—the physical removal of material by mobile agents such as water, wind, or ice.