Historical Geology and Geologic Time Principles

• The exam covers 50 multiple-choice questions, focusing on historical geology, geologic time principles, measuring deep time, and the rock cycle.

Module 1 – What is Historical Geology?

• Historical geology studies Earth's origin and development through time, using the record of past events.
• Paleontology involves studying molecular fossils.
• A hypothesis is an idea or proposition whose truth or falsehood is not initially known.
• Scientific endeavors need to have repeatable observations.
• Earth is approximately 4.56 billion years old.
• The Universe is approximately 13.7 billion years old.

Module 2 – Principles of Geologic Time

• Geology principles include superposition.
• Geology principles include Lateral continuity.
• Geology principles include Original horizontality.
• Geology principles include Cross-cutting relationships.
• Geology principles include Fossil succession.
• Need differentiate between relative and numerical ages.
• Uniformitarianism means "the present is the key to the past".
• There are three types of unconformities: disconformity, nonconformity, and angular unconformity.
• Need to recognize unconformities in diagram form.
• Recognize which unconformity represents the most missing time.
• Cross-sections are used to determine the sequence of events.

Module 3 – Measuring Deep Time

• The geologic time scale was first developed using relative dating methods.
• Correlation is linking rock formations from different places over a long distance.
• Fossil succession is biostratigraphy.
• William Smith created the first geologic map of Great Britain.
• Eras are split into periods, which are then split into epochs of time.
• Atoms consist of orbiting electrons and a nucleus (protons and neutrons).
• Half-life is the time required for one half of a population of parent atoms to decay.
• Zircons are used to age date extremely old rocks.

Module 4 – The Rock Cycle

• Minerals must meet five criteria, beginning with being naturally occurring.
• Minerals must be inorganic.
• Minerals must be solids.
• Minerals must have a defined crystalline structure.
• Minerals must have a definite chemical composition.
• Observations to determine a mineral's identity include color, luster, and cleavage/fracture.
• You should know how to identify quartz, pyrite, calcite, halite, and feldspar.
• Be aware of which minerals will react to acid.
• The strongest chemical bond is covalent.
• The most abundant elements in the Earth's crust (in order) are O, Si, Al, Fe, Ca, Na, K, and Mg.
• The building block of all silicate minerals is the silica tetrahedron.
• Silicates make up more than 90% of Earth's crust.
• Magma is deep in the crust, while lava reaches the surface of the Earth.
• Igneous rock textures include Phaneritic and Aphanitic.
• Igneous rock compositions include Felsic, Intermediate, and Mafic.
• There are connections between types of minerals in the rock names and how much silica content.
• Example: Granite and Basalt.
• A sediment consists of loose fragments of rocks or minerals, shells/fragments, or mineral crystals that precipitate out of water.
• Lithification is the process in which sediment becomes compacted and cemented.
• A metamorphic rock is a rock that has undergone change.
• A protolith is the "parent rock" that undergoes changes in texture and mineral content.
• Example: Limestone turns into Marble.