Lecture 17 Flashcards
What was the first challenge of geology?
How we could get coal if the surface coal was gone. Had to find a method to get coal from the subsurface
How long did it take to calculate the Earth’s age?
300 years
Who was credited with discorvering the first principles of stratigraphy as well as the person who solved the coal problem?
Nicolaus Steno
How many years after the birth of modern science (1660) did people begin to realize the Earth may be older than was believed?
5 years
What were the 2 types of layers discovered by Steno?
One lower, and one upper. Separated by a narrow, harder, iron oxide zone with irregular surface (discontinuity).
What did Steno believe these discontinuties represented?
Traces left by Noah’s ark.
What were the four Principles that Steno came up with?
1) Principle of Layer superposition
2) Principle of Successive Layer Formation
3) Principle of Original Layer Horizontality
4) Principle of Lateral Continuity
What is the principle of layer superposition?
In any sequence of undisturbed layers, the older layer is at the bottom of the succession, younger layers copy a progressively higher position according to age of formation (stratigraphical order)
What is the principle of successive layer formation?
At the time of formation of a layer, only fluid was above it. None of the above existing layers in stratigraphical succession existed at that time
What is the principle of original layer horizontality?
Layers are originally horizontal (or at least parallel to the ones below). Inclinations in layers indicate crustal disturbance
What is the principle of lateral continuity?
Originally deposited strata extend in all directions until they terminate by thinning at the margins of the basin (this one is not entirely true today, so not a true principle).
Which principle demonstrated that Earth may be older than originally thought?
Principle of successive layer formation (2)
