The study of the layers of sedimentary rock at a macroscopic scale
Define the Principle of Original Horizontality
Strata tend to be deposited more or less horizontally
Define the Principle of Superposition
In a vertical succession of sedimentary or volcanic rocks, a higher rock unit is younger than a lower one. “Up” is younger.
Define the Principle of Lateral Continuity
Upon initial deposition, strata tend extend in all directions until they pinch out or until they grade laterally into a different kind of sediment.
Define the Principle of Cross-cutting
A structure that cross-cuts another structure is the younger of the two.
Define the Principle of Inclusion
A structure included in another is the older of the two.
Principle of faunal succession
Fossils in stratigraphic successions change upward (i.e., with time) in a predictable way. For example, strata containing trilobites always underlie strata containing Tyrannosaurus fossils, which in turn always underlie strata with woolly mammoth fossils.
Define index fossils
fossils used to define geological periods
The physical laws of Nature have remained the same since the dawn of time. The Earth may change, but the laws that govern this change do not.
Process by which strata are correlated given their physical attributes
What is lithology
Classification of rock types
A rock unit that can be correlated (mapped) over a certain region and is defined by its observable physical traits (i.e., defined by its lithology, aka rock type).
A rock unit that can be correlated (mapped) over a certain region and is defined by its fossil content.
Define conformable contacts
no significant break (hiatus) in sedimentation has occurred, and the geological record is complete.
Define unconformable contacts
a significant break (hiatus) in sedimentation has occurred due to non-deposition or erosion.
Three methods of dating the earth
Annual layers on trees, estimation of geological rates, and geometric dating
Why does stratigraphy typically require correlation?
a)Because the goal of stratigraphy is to identify large-scale patterns in sedimentary rocks. b)Because outcrops tend to be small and isolated. c)Because proving an event is local or global in extent can help understand how the Earth system operates.
List the ages of the rocks from oldest to youngest
C B A D E
Define a varve
A sedimentary unit deposited in a year.