Journey through the Geologic Time Scale


Within the initial part of the exhibition at the Sirindhorn Museum, we will see a large Geological Time Scale in a rectangular grid engraved on the exhibition floor. The Geological Time Scale is a system of chronological measurement that relates stratigraphy to time and is used by scientists and paleobiologists to describe the timing and relationships between events that have occurred throughout the Earth’s history, from 4.6 billion years ago until the present. The periods of time in Geochronology are Eon, Era, Period, and Epoch accordingly.

To reflect the time scale, the large grid contains a table of geological time spans. In each timetable, a symbol of plants and animals is placed to define the groups of life appearing during that period. Once we walk pass this Geological Time Scale, we will be given an impression that we have walked pass the geological time of 4.6 billion years. It is a quick way to observe and learn about our Earth’s history and the development of life in each period.

The first timetable that we will walk through is called the Precambrian Period which describes the large span of time in Earth’s history, spanning from 4,600-542 million years ago. At that period, the only life found was small single cell creatures that lived in the sea; such as, jellyfish, and coral.

The next time scale is called the Paleozoic Period, spanning from roughly 542-251 million years ago. The Paleozoic Era is subdivided into six geological periods (from oldest to youngest): the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The Paleozoic Era was a time of dramatic geological, climatic, and evolutionary changes. The timetable on the floor thus shows the signs of widespread diversification of life in the Earth’s history including hard-shelled fauna; such as, shellfish, Trilobite, primitive fish, insects, amphibians and even reptiles.

Then we progress into the next timetable called the Mesozoic Era, spanning from 251-65 million years ago, where the dinosaur symbols are present in the timetable. The dominant terrestrial vertebrates; such as, herbivorous sauropods and carnivorous dinosaurs evolved from reptiles and migrated throughout the Earth.

However, after the Cenozoic Era, the mysterious extinction called the “Cretaceous–Paleogene extinction” happened. This event may have contributed to the dinosaurs’ extinction. The next timetable then shows signs of elephants, horses, whales, dolphins, monkeys, representing the age where mammals became prominent and thrived instead of the reptiles.

And the last Geological Time Scale we are at on the floor is called the Age of Man where a symbol of humankind is shown to represent the evolutionary process from the past until the present time.