Stratigraphy -is a branch of geology that studies rock layers, beds, or strata (singular: stratum).
a Catholic priest named Nicolaus Steno formulated the guiding principles of stratigraphy.
Law of Superposition: Younger layers sit atop older layers
Law of Lateral Continuity: Layers are continuous until broken up or disrupted
Law of Original Horizontality: Layers are deposited as flat sheets. Tilting/folding occurs later in time
Law of Cross-Cutting Relations: Any inclusions are younger than the layers they’re found in
intrusion -is an igneous rock body that forms when magma cuts through sedimentary layers and solidifies before it reaches the surface.
William smith -father of English geology, introduced another essential principal
Principle of FaunalSuccession- Sedimentary strata may contain fossils of plants and animals in a definite and invariable sequence.
Principle of Faunal Succession.
A) disconformity
B) angular unconformity
C) non comformity
Disconformity - This type of unconformity is present when there is a missing stratum or strata in the sequence, usually due to a period of non-deposition or erosion.
Nonconformity - This occurs when sedimentary strata are deposited on top of igneous or metamorphic rock bodies
Angular unconformity -When strata are disturbed by forces that cause folding, tilting, and/or faulting, they no longer appear horizontal.