Prospecting

 

Prospecting – разведка, разведочные работы

Deposit (n) – месторождение, залежь

Lead (n) – свинец

Ligneous (adj) – вулканического происхождения, изверженный

Molten (adj) – расплавленный, горячий

Mapping – топографическая съемка, нанесение на карту

Outcropping – выход на поверхность, обнажение (пород), голова пласта

Confirm estimates – подтвердить выводы (заключения)

Sophisticated (adj) – сложный (в научном и техническом отношении)

Prospecting is search for economically exploitable mineral deposits. Up to the 20^th century, prospecting was done by men roaming likely areas on foot and recognizing gold, iron, lead, or other valuable ores by sight. Certain types of mineral deposits are associated with certain types of rock and land forms; copper, lead and zinc, for example, generally appear in igneous rock formed by cooling of masses of molten minerals at or near the Earth’s surface. Geologists can sometimes infer the extent of deposits by mapping outcroppings; drilling is then used to confirm the estimates.

In the 20^th century, more sophisticated techniques were developed as the result of the maturing of the physical sciences and the need to seek minerals beneath the surface. Some valuable minerals, such as iron and copper are magnetic: first the compass and later the more sensitive magnetometer have been used to detect them. The gravimeter, an instrument that can detect minute changes in the Earth’s gravitational field, can be used to detect certain minerals that have densities different from those of the surrounding formations. Some sulfide mineral deposits have undergone partial oxidation, and the resulting non-uniformity in chemical composition creates an electric potential that causes currents to flow in the surrounding ground; voltmeters can be used to detect them. Another electrical method involves implanting electrodes in the ground and tracing the current between them by means of a galvanometer; the current will seek out conductors in the ground.

 

I. Tell your fellow-students what the aim of prospecting is.

II. Tell your fellow-students what methods were used to discover mineral deposits up to the last century.

III. Tell your fellow-students what helps to infer minerals and their extent.

IV. Tell your fellow-students what modern methods are used to make a search for mineral deposits nowadays.

V. Find in the text the synonym for the word complicated.

VI. What heading would you supply with each paragraph?