TellUs: "The Earth Story" Series, Geological Time Introduction

The Earth’s Story Series: Geological Time Intro

For much of the planet’s long geological history its atmosphere wouldn’t have been able to support the diversity of life it does currently. Also the shape and position of its continents would be unrecognisable to us, compared to what they look like nowadays. Our planetary home has experienced long periods of tropical warmth, in which there were no ice at the poles. On the other hand the Earth has also experienced times where a considerable portion of its landmass was buried under deep ice.

The Earth formed with the rest of the Solar System approximately 4600 million years ago. Obviously this is a huge amount of time and needs to be divvied up in order to break it down into manageable chunks, for studying purposes and also to define its multiple, significant changes. 

Geologists have divided the Earth’s history into time intervals based off of rock formations and fossil records. Geologists have equated this time into eons (the longest period), eras which are then subdivided into geological periods. Periods can also be further subdivided into epochs. As opposed to conventional times, like hours, minutes and seconds in which they’re set (60 minutes for an hour etc) geological age differs in length, for how long they last before a new geological age is commenced. Eons, eras and periods originally were marked by a major change in the geological record that indicated a key change in developments at the Earth’s surface. Thus the boundaries between one geological age and another are associated with major changes to the Earth’s climate, atmosphere or evolution process. Most of which tend to happen at the same sort of time. Bear in mind that timings of these ages shown in the diagram below are constantly being updated and altered, as dating methods improve.

The diagram above displays an overview of a geological timeline, from the beginning of our Earth to when humans first appear (this is not a complete timeline, only until approximately 65 million years ago). The second part of the timeline will appear in an upcoming "Earth Story" series blog.

In my next couple of blogs I will go into detail about each geological time period and what the Earth looked like at these times and how it has evolved. After that I will continue onto the last 65 million years and again describe each geological time in detail, so look out for my upcoming blogs in the next few weeks to continue your Earth journey!