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Task 3. Look at Figure 4.4. There are many types of fossilization. Six examples are
shown there. Name the examples A, B, C, D, E, F.

Task 4. Answer the questions:
1. Why are fossils important inclusions in sediment?
2. What is palaeontology?
3. What are the most important types of fossils?

Task 5. Build up a summary of the text.

TEST YOURSELF

Task 1. Tell whether the sentences are true or false. Correct the false ones.
1. During the late XIX and early XX centuries, no attempts were made by the scientists to
determine Earth’s age.
2. Relative dating means placing rocks in their proper sequence of formation.
3. The law of superposition is the most basic principle of relative dating.
4. The principle of original horizontality means that layers of sediment are generally deposited
in a vertical position.
5. The principle of cross-cutting relationships means that when a fault cuts through other
rocks, or when magma intrudes and crystallizes, the fault or intrusion is younger than the
rocks affected.
6. Inclusions are pieces of fossils that are included into the rock.
7. All breaks in the rock record are termed unconformities.
8. Many disconformities are easy to identify because the rocks above and below are different
and there is little evidence of erosion.
9. In a nonconformity the break separates older metamorphic or intrusive igneous rocks from
younger sedimentary strata.
10. Fossils are basic and important tools for interpreting the geologic past.
11. Palaeontology is an interdisciplinary science that blends geology and biology in an
attempt to understand all aspects of the succession of life over the vast expanse of geologic
time.
12. Carbonization is particularly effective in preserving leaves and delicate animal forms.
13. Burrows are animal footprints made in soft sediment that was later lithified.
14. Gastroliths are fossil dung and stomach contents that can provide useful information
pertaining to food habits of organisms.

Task 2. Complete the summary of the unit with the given terms.

Principle of cross-cutting relationships, inclusions, principle of original horizontality,
numerical dates, law of superposition, relative dates
1
The two types of dates used by geologists to interpret Earth history are (1)… … , which
2
put events in their proper sequence of formation, and (2)… … , which pinpoint the time in years
3
when an event occurred. Relative dates can be established using the … … (in an undeformed
sequence of sedimentary rocks or surface deposited igneous rocks, each bed is older than the one
4
above and younger than the one below), the … … (most layers are deposited in a horizontal
5
position), the … … (when a fault or intrusion cuts through another rock, the fault or intrusion is
6
younger than the rocks cut through), and … (the rock mass containing the inclusion is younger
than the rock that provided the inclusion).