The topic for this post is going to be a Timescale Mnemonic
You need to know the order of the periods in the geologic time scale, which is not as difficult as it sounds. make sure you start with the oldest period (the principle of superposition).
Your mnemonic should cover only the eleven periods (listed below), and should be an easily memorized (preferably witty) sentence with the same first letters as the names of the period.
Cambrian – Ordovician – Silurian – Devonian – Carboniferous – Permian – Triassic – Jurassic – Cretaceous – Tertiary – Quaternary