C HAPTER 6 LESSON 1-4 By: Kaylynn Priday Sam Davis

V OCABULARY LESSON 1 Uniformitarianism- is a principle that states that the same geologic processes shaping the Earth today. Catastrphism- is a principle that states all geologic change occurs suddenly.

V OCABULARY LESSON 2 Relative Dating- determining weather an object or event is older or younger than other objects or events. Superposition- is a principle that states that younger rocks lie above older rocks in undisturbed sequences. Geologic column- is an ideal sequence of rock layers that contains all the known rock and fossil formations on Earth arranged oldest to youngest. Unconformity- a surface that represents a missing part of the geologic column.

V OCABULARY LESSON 3 Absolute dating- is the process of establishing the age of an object, such as a fossil or rock layer, by determining the number of years it has existed. Isotopes- are atoms of the same element that have the same number of protons but have different number of neutrons. Radioactive Decay- radioactive isotopes breaking down into stable isotopes of other elements. Radiometric Dating- determining the absolute age of a sample based on the ratio of parent material. Hafe-life- the time it takes for one-hafe radioactive sample to decay.

V OCABULARY LESSON 4 Fossil- any naturally preserved evidence of life. Permineralization- a process in which fill in pore spaces of an organism’s tissues. Petrification- occurs when the organism’s tissues are completely replaced by minerals. Trace Fossil- any naturally preserved evidence of an animals activity. Coprolites- are preserved feces of animals. Mold- is a cavity in the ground or rock where a plant or animal was buried. Cast- is an object where sediment fills in a mold and becomes a rock. Index Fossils- fossils of an organism that lived during a relatively short, well-defined time span.

U NIFORMITARIANISM What's the difference? Uniformitarianism is a principle that states that the same geologic process shaping the Earth today have been at work throughout Earth’s history. Catastrophism is a principle that states that all geologic change occurs suddenly. Scientists had thought the Earth formed by catastrophism

RELATIVE DATING Determining weather an object or event is older or younger than other objects or events. The Geologic Column Is an ideal sequence of rock layers that contains all the known fossils and rock formations on Earth arranged from oldest to youngest. When geologists are not sure about the age of a rock sequence they are currently studing, they gather information about the sequence and compare it to the geologic column.

Disturebed Rock Layers Fault Is a break in the Earth’s crust along which blocks of the crust slide relative to one another. Intrusion Is molten rock from the Earth’s interior that squeezes into exsiting rock and cools. Folding Occurs when rock layers bend and buckle from Earth’s internal forces. Tilting Occurs when internal forces in the Earth slant rock layers without folding them.