GEOL 125: Earth History

 Study Guide #5 (F04)

What are the characteristics of a mineral? What properties can be used to identify minerals? Is the ratio of Si to O in olivine (a mineral) always the same? Is this ratio of Si to O always the same in a granite? Why?

What is a rock? What criteria are used to classify rocks? Draw a diagram illustrating the Rock Cycle. How is the Rock Cycle related to tectonic movements in the earth? Where in the earth do the following rock types form? (granite, gabbro, rhyolite, basalt, limestone, evaporites, sandstone, shale, conglomerate, slate, schist, gneiss, marble).

How is the texture of an igneous rock related to its cooling rate? Why do bands develop in metamorphic rocks? How can we heat a rock to cause metamorphism?

How are sediments produced? What processes lead to lithification of sediments into sedimentary rocks? What factor determines the size of grains in sedimentary rocks? What determines the shape of grains (round or angular) in sedimentary rocks? What clues may be observed in sedimentary rocks that provide information about the nature of the environment in which they formed (sub-aerial/marine; high-energy/low energy; water depth, etc.)?

What are transgressions and regressions? What events might make these occur? How can you recognize these changes by looking at sedimentary rocks?

How can we determine the relative timing and sequence of geologic events in a region from observations of the rock record? Practice using the handout given in class.

How can we correlate the relative ages of rocks in two distant places? How can we determine the absolute age of rocks?

What is the geologic time scale? You should know all eons, all eras during the Phanerozoic, all periods since the Cambrian, and all epochs of the Cenozoic. How are boundaries in the geologic time scale determined?

What are Uniformitarianism (Actualism) and Catastrophism? How can each be used to explain the rock record?

Terms to know
 crystal face  crystal lattice  cleavage
 hardness  Moh's scale  streak
 silica tetrahedron  igneous  metamorphic
 sedimentary  foliation  texture
 porphyritic  bedding plane  fossil
 turbidity current  graded bedding  volatile
 sorting  transgression  regression
 facies  delta  cross-bedding
 aeolian  marine  unconformity
 Law of Superposition  Nicolas Steno  Law of Original Horizontality
 high-energy environment  low-energy environment  granite
 rhyolite  basalt  gabbro
 limestone  shale  evaporite
 slate  schist  gneiss
 geologic formation  index fossil unconformity
cross-cutting relationships  James Hutton  Charles Lyell
 William Smith  Georges Cuvier  erosion
 chemical weathering  physical weathering  deposition
 detrital sediments chemical sediments  precipitation
 cementation  compaction  angular unconformity