Stratigraphy Flashcards
What is stratigraphy?
It is a technique used to organise sedimentary rocks. It looks at the boundaries of the layers, this then shows what environment the rock was formed in and how the environment has changed.
E.g places on land such as a farmers paddock found shark teeth in them indicating that this land was once under the sea.
What area and country show the same environmental change?
Martinborough sheep station and Antarctica glacier.
What are Steno’s three principles?
- Principle of superposition
- Original horizontally
- Original lateral continuity
What does the first principle “superposition” mean?
In any layered sequence of rocks, the top layer is the youngest and gets OLDER as you go DOWN the sequence.
UNLESS they have been turned by TECTONIC (subducting) activity.
What does the second principle “original horizontally” mean?
This means that the layers resulting from particles deposited under the influence of gravity are originally PARALLEL to the surface of the Earth.
They are changed due to folding and uplifting.
What does the third principle “original lateral continuity” mean?
Means layers, when they were originally formed they were laterally continuous UNLESS they terminated against another SOLID substance (originally horizontal e.g bent through a mountain range).
Mars:
Has layers some are continuing and the only way they can be formed/sediment deposited is by water. Therefore, there was once water n mars (no water for the past 43 million tears).
An example of original lateral continuity
Mars: has layers some are continuing and the only way they can be formed/sediment deposited is by water. Therefore, there was once water n mars (no water for the past 43 million tears).
