Fig. 45. Three types of plate boundaries

Geophysicists also talk of active margins (where colliding continental and oceanic plates spark off volcanic eruptions, earthquakes and mountain building) and passive margins (tectonically quiet boundaries between continental and oceanic crust).

(Lambert “The Field Guide to Geology” 1988, Cambridge University Press)

Discussion questions:

1. What comprises the Earth’s surface?

2. What is a plate?

3. What do the plates make up?

4. What shifts the plates?

5. How many types of plate margins are there?

6. What is

- a constructive margin

-a destructive margin

-a conservative margin

7. What is the difference between active and passive margins?

8. The map shows major plates. Name them.

PART 2: CONTINENTAL CRUST

1. Comprehension

1.1 Vocabulary

Pay attention to the pronunciation of the geographical terms and especially to the pronunciation of numbers (R.P.-8.2.3)

Tethyan (Alpine-Himalayan)	Aleutian Islands
Circum-Pacific	The Andes
Ural Mountains	The Alps
	Cordillera

Pay attention to the terms and expressions in bold

plateau	плато, плоскогорье
range (ranges)	горный хребет (горная страна)
mountain chain (range)	горная цепь
mountain system	горная система
orogenesis	орогенез, горообразование
to disrupt	нарушать
mobile belt	подвижный пояс
lithospheric plate	литосферная плита
crustal deformation	деформация земной коры
mountain building	горообразование
orogen	ороген, горно-складчатое сооружение
orogenic	орогенический; горообразующий
uplift	поднятие (участка земной коры)
to weld (together)	соединять
scrap	скрап; обломок
to sweep	перемещать; сносить
terrane	террейн
to squeeze	сдавливать; выжимать
to bob up	возникать
to ruck up	нагромождать, собирать(ся) складками
to shrink	сокращать
alien rock	«чуждые» породы

1.2 Mountain building (r.P – 8.2.7, 8.2.8, 8.2.9)

Large regions of the Earth consist of mountains. Most occur in rows called ranges. Parallel ranges and intervening plateaus form chains such as the Andes and North American Cordillera. Related mountain chains and ranges make up mountain systems, notably the Tethyan (Alpine-Himalayan) and Circum-Pacific systems.

Orogenesis, or mountain building, occurs along mobile belts – places where colliding lithospheric plates disrupt the continental crust. Such mountain-building belts are known as orogens and orogenic belts are belts of fold mountains – mountains created by crustal deformation and uplift. Geologically recent orogenic belts mostly rim continents. But ancient orogenic belts (the Ural Mountains for example) can occur deep inside a continent where lithospheric plates were welded together long ago.