ava-~pp~ " made of rock-- contains mlnerol-<br > butle limestone calcite<br > Look for Surface Forms These are evident in<br > the physical forms seen on the surface-hills， valleys， cliffs，<br > and basins. Some forms and structures are associated with<br > a particular type of rock and can be recognized at a dis-<br > tance， Knowing forms and structures does more than help<br > you find rocks and minerals. It aids you in interpreting lhe<br > landscape， so that you can read dramatic chapters of<br > the history of the earth， Rock structures are dealt with<br > under rocks (pp. 121-145). Physical geology treats them<br > in greater detail.<br > Lank for Rocks These are the materials of which<br > the crust of the earth is made. They form the mountains<br > and underlie the valleys. You see them when they have<br > been pushed or folded upward or when they jut through<br > soll to form an outcrop. All minerals occur within rocks，<br > and often are components of rocks. Rocks include the solid<br > bedrock and also the unconsolidated debris above it，<br > called the mantle.<br > Look for Minerals These are the bricks of which<br > the earth itself is made. They are inorganic chemical<br > elements or compounds (some quite complex) found nat-<br > urally in the earth. Because each is a chemical or a mix-<br > ture of closely related chemicals， a mineral has fairly<br > definite and stable properties.<br >