What is Science?
The systematic study of the structure and behaviour of the physical and natural world through observation, experimentation and theories
Steps in scientific investigation
-Raise a question about the natural world
-Construct a hypothesis that may answer the question
-Develop observations and experiments to test the hypothesis
-Collect scientific data
-Analyse data
-Results support/ do not support/ partially support hypothesis
- Try again
-Share and peer review
What are the branches of geology?
Physical Geology (affects earth now) and
Historical Geology
(history of the earth)
What is Physical Geology?
This focuses on
- the materials that make up the earth
-processes that shape the surface & interior
-mineral and rock formation (WEDEV)
What is the purpose of physical Geology?
To explain current geological events and make predictions based on them.
What is Historical Geology?
This is the Earth’s History (evolution of life & earth’s structural changes over time)
-fossils (rock strata)
- plate tectonics
-the geological timescale
What is the purpose of Historical Geology?
To reconstruct the sequence of past geological events and understand the history of the earth and its inhabitants.
(location of oil and gas)
What is the principle of uniformitarianism
The present is the key to the past.
Laws that operate today (biological, chemical and physical) have also operated in the past.
Relative dates
Puts events in their proper sequence of formation
Numerical dates
Pin point the time in years when an event took place.
(Radioactivity)
Principle of Superposition
This principle states that in an undeformed sedimentary rock each layer is younger than the one below it and older that the one above it.
Principle of Horizontality
This states that sediment is deposited horizontally and any incline is because of processes like tectonic activity, faults, mountain folding etc.
-If the rock layers are flat it means it has not been disturbed and still has original horizontality
Principle of Lateral Continuity
This states that beds are continuous layers that go in all directions until it grades out into a different type of sediment or thin out at the edge of the basin of deposition.
Principle of Cross Cutting Relationships
Any features that cut across rocks must have formed after the rocks they cut through.
eg. faults
Principle of Inclusions
A rock mass next to the one containing the inclusions must have been there first in order to have provided the rock fragments.
Conformity
When we see rock layers that have been deposited without interruption we call them conformable.
What is an unconformity?
An unconformity refers to a long period in time where deposition ceased.
-erosion removed previously formed rocks and then deposition resumed
- uplift and erosion are followed by subsidence and renewed sedimentation.
* They represent significant geological events in Earth’s history
What are the three types of unconformities?
- Angular unconformity
-Discontinuity
-Non conformity
What is an angular unconformity?
During a pause in deposition, a period of deformation: folding/tilting and erosion occurred .
What is a disconformity?
A gap in the rock record where erosion rather than deposition occurred.
What is a non conformity?
Younger sedimentary strata overlie older metamorphic/intrusive igneous rocks
Who is the father of Geology?
James Hutton (Scottish)
The Siccar Point Unconformity
-James Hutton tried to explain geological phenomena in a scientific method rather than biblical terms.
-East Coast of Scotland
- Angular unconformity
-Silurian-Devonian
What was James Hutton hypothesis?
Younger strata were deposited as unconsolidated sediment on the eroded surfaces of upturned and much older rocks that have undergone the effects of deep burial, heat and pressure.
