A young man named Charles Lyell had different ideas. He wrote a book about them called Principles of Geology. The earth，according to Lyell，was not only thousands of years old，it was millions of years old. As to the common belief that changes in the earth’s surface happen suddenly because of a single earthquake or flood，he said that this might happen once in a while，but usually these changes took place very slowly. He believed that the surface of the earth had been changing from the beginning of time. The changes，he said，were caused by the long-term action of the winds and seas，and by forces such as volcanoes breaking out under the earth’s surface. Once in a great while he thought，a mountain might appear for the first time after an earthquake. But usually mountains would rise slowly and steadily.
Professor Henslow was interested in Lyell’s ideas，but he did not actually believe them. Charles Darwin could not make up his mind about them. But they set him thinking along lines which would later change the beliefs of thoughtful people all over the world.
At Cambridge，Charles Darwin studied just enough to pass the examination，and received his college degree in 1831.During this time，he had become more and more interested in geology. At the end of the school year，he went to North Wales with one of his teachers to examine the rock formations (构成) and to search for fossils. Fossils are the remains of ancient living things. They are usually found fixed in rocks in the earth’s crust (地壳). Fossils may be of animals，such as fish，insects，birds，or humans. They may be of plants from tiny leaves to huge trees.
When a living creature dies，it usually decays (腐烂)or is eaten by animals. However，if it sinks into a riverbed or is quickly covered by the blowing sands of a desert storm，the bones are kept up in the earth. Over many years the soft inner parts of a bone disappear，leaving the inside hollow. Water containing mineral enters into the hollow. Slowly the mineral hardens and makes the bone hard and heavy，like stone.
71.According to Charles Lyell，it is mainly        that the earth has been formed like today’s shape.
A. from the beginning of time                           B. past some experiences of big flood
C. over a very long period of years                    D. because of several big earthquakes
72.Charles Lyell believed the fact that a mountain is formed         .
A. more by seas than by volcanoes                     B. more slowly than suddenly
C. more by an earthquake than by winds      D. more steadily than quickly
73.Unlike Professor Henslow，Charles Darwin         .
A. never thought Lyell’s ideas were right
B. did made up his mind not to accept Lyell’s ideas
C. thought about what the world were then thinking about
D. thought over Lyell’s ideas and developed them
74.The main purpose of Darwin’s going to North Wales was to         .
A. make a study of fossils
B. appreciate the rock formation
C. to do research work into dead animals
D. look for plants from tiny leaves to huge trees
75.In which order are fossils formed?
a. A living thing sinks into a riverbed or sands.
b. Water goes into a bone hollow together with mineral.
c. Something soft in a bone disappears.
d. The hardened mineral makes the bone hard.
e. The bone becomes hollow inside.
A.a b c d e             B.c a b e d                    C.a c e b d                    D.e c d b a