%Relative Age Dating Flashcards
What is unconformity?
An unconformity is a surface where rock has eroded away, producing a break, or gap, in the rock record.
What is Relative age dating?
Relative age is the age of rocks and geologic features compared with other rocks and features nearby.
What are the three types of unconformity?
Disconformity- younger sedimentary layers are deposited on top of older, horizontal sedimentary layers that have been eroded.
Angular unconformity- sedimentary layers are deposited on top of titled or folded sedimentary layers that have been eroded.
Nonconformity- younger sedimentary layers are deposited on older igneous or metamorphic rock layers that have been eroded.
What is correlation?
Matching rocks and fossils from separate locations is called correlation.
What is superposition?
Superposition is the principle that in undisturbed rock layers, the oldest rocks are on the bottom.
What is original horizontality?
The rocks are placed horizontally, but can get tilted.
What is lateral continuity?
Layers are deposited in continuous sheets in all directions until they thin out or hit a barrier. A river might cut through the layers, but the order of the layers does not change.
What is an inclusion?
A piece of an older rock that becomes part of a new rock is called an inclusion. According to the principle of inclusions, if one rock contains pieces of another rock, the rock containing the pieces is younger than the pieces.
What is an index fossil?
Index fossils represent species that existed on Earth for a short length of time, were abundant, and inhabited many locations.
