Toilet roll geologic timescale

In this activity, students construct a modified geologic timescale using a roll of toilet paper. Each piece of the toilet roll represents a time period, and major New Zealand geologic events are to be marked on the paper.

By the end of this activity, students should be able to:

understand that time periods in the geological history of the Earth are exceedingly long
recall that geologic time is for convenience sectioned into eons, eras, periods and epochs
put into the context of geologic time some of the changes that have shaped the evolution of the landscape of modern New Zealand
better understand the terms Oligocene and Miocene in relation to New Zealand limestones
realise that, in this analogy, the length of one toilet roll is representative of only 65 million years in the 4.6 billion year geologic record of the Earth.

Discovery of temperate limestones

Professor Cam Nelson explains how his study of limestones in the King Country region led him to conclude that they were formed in cool temperate environments. At that time, it was believed that all shelf limestones had a tropical origin. Cam’s work was instrumental in developing the temperate cooler water limestone model that now sits alongside the tropical warm water model.

Points of interest
Some of the micrographs and samples shown in this clip:

Micrographs a and d: – thin section images (x40) of bryozoan-dominated temperate limestone
Micrograph b: Ōtorohanga limestone thin section showing an abundance of bryozoan and small foraminifera skeletons.
Sample c: Sediment referred to as ‘bryomol’ – rich in the skeletal remains of bryozoans and molluscs. Dredged from the seafloor off Three Kings Islands to the north of New Zealand.

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