sci. 3-2 relative dating: which came first? pages 59- 63
TRANSCRIPT
A. Relative Dating- determining whether an object or event is older or younger than other objects or events.
B. The Principle of Superposition- states that younger rocks lie above older rocks as long as the rocks have not been disturbed.
C. Geologic Column- an ideal sequence of rock layers that contains all the known fossils and rock formations on Earth arranged from oldest to youngest.
D. Disturbed Rock Layers1) fault- a break in the Earth’s crust
along which blocks of crust slide relative to one another.
E. Unconformities- when a layer or several layers of rocks are missing from a rock layer sequence, a gap
1)Means missing time, time not recorded by rock layers
F. Types of Unconformities1) Disconformity- exists where part of a
sequence of parallel rocks layers is missing ( Hard to see, most common)
2) nonconformity- exists where sedimentary rock layers lie on top of an eroded surface of nonlayered igneous or metamorphic rock.