Active learning ideas
Stratigraphy is the study of rock layers and the 'deep time' they represent. In this topic, students learn the fundamental laws used to sequence Earth's history, such as the Principle of Superposition (older rocks are at the bottom) and Cross-Cutting Relationships (a fault is younger than the rock it cuts). They also investigate unconformities, which represent 'missing time' in the geological record due to erosion.
Activity 01
Groups are given a complex diagram of rock layers, intrusions, faults, and unconformities. They must work together to list the events in order from oldest to youngest, providing a 'law' (e.g., Superposition) to justify every single step.
How do geologists determine the relative age of rock strata?
Activity 02
Students start with 100 pennies (representing radioactive isotopes). They shake and spill them, removing all 'heads' (decayed atoms) each round. They plot the results on a graph to see the exponential decay curve, helping them understand how carbon or uranium dating works.
What is an unconformity?
Activity 03
Students create a timeline of Earth's history scaled to a 24-hour clock. They place key events (first life, dinosaurs, humans) on the clock and display them. This helps them visualise the vastness of 'deep time' compared to human history.
How does radiometric dating provide absolute ages?
A few notes on teaching this unit
Watch Out for These Misconceptions
Carbon dating can be used for dinosaur bones.
Carbon-14 has a very short half-life (about 5,700 years) and is only useful for samples up to 50,000 years old. For dinosaurs, we use isotopes with much longer half-lives, like Uranium-Lead. Peer discussion of 'the right tool for the job' helps clarify this.
An unconformity is just a gap between two rocks.
It is specifically a surface representing a period of erosion or non-deposition. Using physical models of 'depositing, tilting, eroding, and re-depositing' helps students see that an unconformity represents a huge amount of lost geological history.
Methods used in this brief
Evolution of Life and Key Fossil Groups
This topic examines the fossilisation process and the morphology of major fossil groups such as trilobites, ammonites, and graptolites. Pupils will use fossils as zone fossils for correlation.
8 methodologies
Mass Extinctions and Climate Change in the Geological Past
Pupils will investigate the causes and evidence of major mass extinction events, such as the K-Pg boundary. They will also explore how geological evidence records past climate changes.
8 methodologies