What is uniformitarianism?
geological processes that occurred in the past can be explained by current geologic processes
Who invented Uniformitarianism?
James Hutton
Who was Charles Lyell?
British geologist who supported uniformitarianism and was called the Father of Modern Geology
What is catastrophism?
changes in the earth's crust in the past have resulted from sudden events.
What is relative age?
the age of an object in relation to the ages of other objects
What is absolute age?
The numeric age of an object or event
What is unconformity?
a gap in the geologic record
What is radiometric dating?
determining the age of an object by comparing relative percentages of a radioactive isotope and a stable isotope
What is an isotope?
Atoms of the same element that have different numbers of neutrons but the same number of protons
What isotope do we use to date rock layers?
Uranium 238
What isotope is used for things that have lived in the past 70,000 years?
Potassium 40
What is a fossil?
the remains of an organism that lived long ago preserved in sedimentary rock
What is an index fossil
A widespread and distinct fossil that establishes the age of rock layers
Example of an index fossil
Trilobites
What is a geologic column?
an arrangement of rock layers in which the oldest rocks are at the bottom
What is a geologic time scale?
a record of the life forms and geologic events in Earth's history
What geologic time do we live in now?
Cenozoic era
Study chart on 231 pleeze
pleeze and thank u
What does evolution mean?
The process of change by which new species develop from preexisting species over time
What is Precambrian time?
The time from Earth's formation to the beginning of the Paleozoic era
What lived in the Precambrian Era?
stromatolites; layered reef like deposits
Why do we change eras of time?
geologic time is divided using significant events in the history of the Earth
What is the impact hypothesis?
the Moon formed out of the debris left over from a collision between Earth and an astronomical body the size of Mars in the Hadean eon
What are the four eras of geologic time?
Cenozoic, Mesozoic, Paleozoic, Precambrian time
What are the major divisions of geologic time?
eons
What is the law of superposition?
oldest on bottom, youngest on top