532 The Earth and Its Inhabitants Change unit x 



4. If a large, shallow, waterproof box is available you may watch sedi- 

 mentation on a small scale. Send a stream of water carrying sand into one 

 end of the box; the overflow can pass out the other end through an open- 

 ing at the bottom of the side. What happens? Why? Now send water 

 carrying mud into the box. Describe what happens. Explain. 



5. DeiJioiistration of types of rock. Examine samples of sedimentary, 

 igneous, and metamorphic rocks. In general, which are the hardest? 

 Which the softest? 



6. It is possible to imitate the formation of an imprint fossil bv the use 

 of plaster of Paris. Use vaseline on the object (a scallop shell is suitable) 

 so that the plaster will not stick to it. Two types of fossils may be formed, 

 one showing the outside of the shell, the other the inside. Both types are 

 found in the rocks. 



7. Examine the difi^erent types of fossils provided in a standard set. 

 Which are the unchanged remains of plants and animals? What kinds of 

 changes may take place in the organism as fossilization goes on? Are 

 there fossils which do not contain any part of the organism, changed or 

 unchanged? 



Further Activities in Biology 



1. Look through back numbers of the National Geographic Magazine 

 and report to the class on earthquakes or volcanoes. The story of Pari- 

 cutin is told in Life as well. 



2. Using two flat rocks and some packed, wetted soil, demonstrate how 

 the slipping of the underlying rock causes rifts in the soil or displace- 

 ments. 



3. Prepare a short report on the "bad lands" of the West. Explain how 

 they were formed and why the soil is not yet completely washed away. 

 Consult a geology or physiography textbook. 



4. If you are interested in photography, take pictures of lakes which 

 seem to be in difi^erent stages of change. Arrange them in a series and 

 mount them to demonstrate how a lake disappears. 



5. The camera is the best recorder of all types of earth changes. Why 

 not prepare a list of subjects such as a bare slope before and after a heavy 

 rain? 



6. Start now to make a fossil collection. You will be surprised to learn 

 how common fossils are in many parts of the country. 



7. Read some of the books written by Carroll Lane Fenton and Roy 

 Chapman Andrews. Report briefly to your class. (See bibliography.) 



8. By reference to clicmistry texts find out how scientists have meas- 

 ured the rate at which uranium becomes lead. Explain this briefly to the 

 class. How does the scientist know that the lead came from uranium? 



