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WJEC GCSE Geology
Theory Paper - external assessment 75% 1½hr - 100 marks
An on-screen non-tiered written paper consisting of compulsory structured data and stimulus response questions,
marked by WJEC.Controlled internal assessment 25% 50 marks
Option 1Directed investigation of a virtual location presented as 'field'
notes and a written report. Marked by centre.Or
Option 2Directed investigation of an actual location presented as field
notes and a written report. Marked by centre.
“The Present is the key to the past”
“While the end goal lies, kilometers, days, weeks, years away, it is today that counts. It is what you do today, right now, this moment, on this day that you will look back on with pride, from which you will derive immediate joy and in the end satisfaction, regardless of how it turns out.”
Pete Vordenberg (US National Cross Country Skiing Coach)
Why is paper white?
What does the centre of the Earth look like?
Is the Earth’s atmosphere getting hotter?
How do we know?
Deciphering Earth’s History
Learning Objectives:To understand the principle of
UniformitarianismTo know the concepts of original horizontality, comformability and
superposition.
Langstone Rock
Geology is one of the newest Sciences.In the mid 1600’s it was thought that the Earth
was only a few thousand years old – many people accepted this as it fitted with Christian Beliefs.
By the seventeenth and eighteenth centuries a ‘doctrine of catastrophism’ was developed.
Catastrophists believed that the Earths landscape had been developed primarily by sudden and great worldwide catastrophies.
Geology in the Past
Birth of Modern Geology
Modern Geology began in the late 1700’s with James Hutton’s publication of his Theory of the Earth.
He put forward a fundamental principle that is the pillar of geology today: Uniformitarianism.
It simply states that, the physical, chemical and biological laws that operate today have also operated in the geological past.
Some Fundamental Principles
The Law of Superposition
A Dane, Nicolaus Steno, working in Italy in 1669, recognised a series of events in an outcrop of sedimentary rock layers. He applied a very simple rule, the law of superposition.
The law states that in an undeformed sequence of sedimentary rocks, each bed is older than the ones above it and younger than the ones below it.
The Grand Canyon
The Principle of Original Horizontality
Steno is also credited with recognising the importance of another basic principle, called the Principle of Original Horizontality.
The layers of sediment are generally deposited in a horizontal position.
Thus, if we observe rock layers that are flat, it means they have not been disturbed and still have their original horizontality.
Anticline and Syncline
Law of Cross-Cutting Relationships
A rock or structure must be younger than any rock or structure it cuts across. For example a dyke must be younger than the sediments pierced by it.
What was the order of events?
What happened here?
Unconformities
An unconformity represents a long period during which deposition ceased, erosion removed previously formed rocks, and then deposition resumed.
There are three types of Unconformity;An Angular UnconformityA DisconformityA Nonconformity
Angular Unconformity
Siccar Point in Scotland
Disconformity
Nonconformity