Cambridge B2 First

B2 First - Reading Multiple Choice

The Earth's Tectonic Plates

Read about the Earth's tectonic plates, then answer the questions about the text, choosing either A, B, or C as the best answer.

Most earthquakes are caused by large-scale movements of the Earth's lithospheric plates. and occur at the boundaries between the plates. Experts recognize seven to twelve major plates and a number of smaller ones. The plates take their names from continents (the North American plate): from oceans (the Pacific plate): and from geographic areas (the Arabian plate).

Slow and Steady Motion

The plates are in very slow but constant motion, so that seen from above, the Earth's surface might look like a slowly moving spherical jigsaw puzzle. The plates move at rates of 2 to 15 cm or several inches in a year, about as fast as our fingernails grow. On a human scale, this is a rate of movement that only the most sophisticated instruments can detect. But on the scale of geological time, it's a dizzying speed. At this rate, those almost-four-billion-year old rocks could have traveled all the way around the Earth eleven times.

The movement of the plates is generally one of three kinds: spreading, colliding or sliding. When plates are spreading, or separating from each other, we call their movement divergent. When they are colliding, or pushing each other, we call the movement convergent. Movement in which plates slide past each other is called lateral (or transform) plate movement. Earthquakes can accompany each of the three types of movement.

Plate Tectonics

The revolutionary theory of plate tectonics originated early in the 20th century, although it did not gain general acceptance until the late 1960s. The German meteorologist, geophysicist, and explorer Alfred L Wegener is now given credit for the first step in understanding the movement of the lithosphere. In the period 1910-1912 he formulated the theory called continental drift and collected evidence from the rocks, fossils, and climate of various continents to show that they had once been joined together. Wegener had little data on the oceanic crust, so he thought that the continents merely moved through that crust.

1. Earthquakes occur when what parts of the tectonic plates collide?

    the edges

    the centres

    the peaks

2. Tectonic plates can get their names from what?




3. Why is the phrase "jigsaw puzzle" used in the second paragraph?

    to show how complex everything is

    because of the way the plates fit together

    because of the number of plates

4. Why have the plates travelled so far?

    because they are moving quite fast

    because Earth is not very big

    because of the age of the Earth

5. Can earthquakes be caused when plates are moving away from each other?



    only if they are touching

6. Why did Wegener's theory take so long to be accepted?

    he had no understanding of the ocean floor

    it was very different from previous ideas in this area

    he made several errors in his theory

7. What evidence did Wegener NOT use to support his theory of Continental Drift when looking at two now-distant locations?

    the existence of similar rocks

    the existence of similar extinct animals

    the existence of similar races of people

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