Section II.
Elements. Minerals. Rocks.
Unit I. Oxygen and its Role in the Earth’s Interior
Focus on:
1. èíòåðíàöèîíàëüíàÿ è òåðìèíîëîãè÷åñêàÿ ëåêñèêà;
2. ñëîâà, îáîçíà÷àþùèå ñîñòàâ, ñòðîåíèå, ïðåîáðàçîâàíèå âåùåñòâ;
3. ñëîâîîáðàçîâàíèå: wide – widely, increase – to increase, colourless;
4. mean/means – çíà÷åíèå è óïîòðåáëåíèå;
5. ñòåïåíè ñðàâíåíèÿ ïðèëàãàòåëüíûõ è íàðå÷èé;
6. êîíñòðóêöèÿ the more … the less;
7. óïîòðåáëåíèå «neither … nor», «both … and», «like/ unlike», «while»;
8. «trouble spot»: the former; the latter; formerly; formally; late; later; letter;
9. ïîñòðîåíèå äåôèíèöèé.
Text Study
Elements are chemical substances that can not be broken down into simpler chemical substances by chemical means.
Oxygen is the most widely spread element of the earth’s crust, constituting almost 50% of its mass. It is a colourless, odourless, tasteless gas, slightly soluable in water, and slightly heavier than air. Oxygen is the most chemically active substance known.
Under conditions of ordinary temperature and pressure oxygen is known as a stable element occurring in large quantities in a free state. In combination with hydrogen and carbon it forms in the surface zone the very widely spread compounds – water and carbonic acid gas. Both these combinations are highly active agents in the formation and destruction of minerals.
As it gradually penetrates deeper into the lithosphere where temperature and pressure show a steady increase, oxygen becomes more and more active. No other element can be compared in its chemical energy with oxygen when it reaches the deep lying strata of the lithosphere.
Due to its high degree of activity oxygen evidently occurs in the magma only in combination with other elements. Molten magma contains large quantities of both oxygen and hydrogen. In cooling it gives off enormous quantities of these gases, which immediately combine to form water. The latter is an extremely active agent in the interior lithosphere and is referred to as “juvenile” water. These juvenile waters take part in the formation of the co-called mineral veins.
Thus, in spite of its lower content in the deeper zones of the lithosphere, oxygen’s role in the earth’s interior is enormous.