Coker Earth science unit 7 Flashcards
What is the law of Original horizontally?
All sedimentary rock layers and some extrusive igneous rocks are originally deposited in horizontal layers
What is the law of superposition?
In undisturbed rock, the layers on the bottom are older than the layers on top
What is the law of disturbed rock strata?
Any process which disturbs the rock must be younger than the rock it disturbs
What is the law of crosscutting?
Any feature that cuts across layers of rock must be younger than all the layers it cuts across
What is stratigraphy?
A branch of geology dealing with rock layers (strata) and the sequence of events that created them.
Basically the laws
What is uniformitarianism?
The idea that the same geologic processes we see at work today, have occurred in the past
What is relative dating?
The age of something compared to something else
What is tilting?
A type of disturbance that tilts rock layers. Caused by plate movements
What is folding?
A type of disturbance that folds rock layers. Caused by plate movement
What is a fault?
A fracture in the crust along which the lithosphere moves. Caused by plate movement. It displaces rock units
What is an intrusion?
Magma that cuts unto rock layers and cools below earth’s surface forming igneous rocks. Caused by rising magma. It cuts through existing rock and contact metamorphism of existing rock
What is a dike?
Igneous rock intrudes along fractures in the existing rock. It could be vertical or horizontal
What is a sill?
Igneous rock intrudes along sedimentary layers and is horizontal
What is a batholith?
The large mass of igneous rock with irregular shape
What is inclusion?
Parent rock breaks off into magma and does not melt and is found in the cooled igneous rock
What us extrusion?
Molten rock that reaches Earth’s surface (lava) and cools forming igneous rock. Caused by rising magma that reaches the surface. It creates a horizontal layer on top of the existing rock and contact metamorphism of existing rock
What is uplift?
A type of disturbance that raises up a large area of earth’s crust which is caused by plate movement (convergent; continent vs continent). It raises rock units above sea level and exposes rock unit to erosional agents
What is subsidence?
A type of disturbance that lowers a large area of earth’s crust which is caused by plate movement. It lowers rock units below sea level and exposes rock units to deposition of new sedimentary layers
What is unconformity?
A gap in the rock record where layers have been eroded and new layers have been deposited on top.
The steps are deposition, uplift, erosion and subsidence, and deposition
