Download More Principles of Relative Dating Note 2 Inclusions:

More Principles of Relative Dating Note 2
Inclusions:
- pieces of one rock are contained
(included ) in another
- Included rock is the remains of the older
rock (usually sedimentary)
- rock that has included pieces is younger
(usually igneous)
Unconformities
Unconformity– long period when deposition
stops, then erodes, and then deposition
starts again
- (Basically a break in the rock record)
Types to identify
A. Angular: tilted rocks overlain by flat
strata (beds); tops of tilted rocks eroded
B. Nonconformity: new (igneous) rocks
intrude from below and displace older one
C. Disconformity:not easily identifiable
- (usually shown with a wavy line)
- deposition ceased then started again
much later
- this gives a large age gap between 2
layers
Example of Principle of Original
Horizontality
Examples of Cross-Cutting Features
(Dikes)
Another Cross-Cut Feature (Dike)
Practice Cross Cut View
Folds:
When rocks have an unconformity (time
break), they are often folded by tectonic
stresses within the Earth
These generally take 2 shapes
A. Anticline (rocks arch up)
B. Syncline (rocks sink down)
Examples of Anticlines
Examples of Synclines