Triassic Period

Following the "Great Dying" extinction at the end of the Permian, the Triassic Period (252 to 201 million years ago) marked the beginning of the Mesozoic Era. This was a time of immense geological building and biological resilience.

1. Building the Otter Sandstone

The most prominent geological feature from this time in Sidmouth is the Otter Sandstone Formation.

• The Environment: These rocks were formed in a hot, arid landscape characterized by vast sand dunes and "ephemeral" lakes that would appear and disappear with the seasons.

• The Rocks: Characterised by their iconic reddish-brown colour, these layers contain fluvial (river) sediments and evaporites like gypsum and halite (salt), left behind when ancient lakes dried up.

2. Life on a Divided Supercontinent

During the Triassic, the supercontinent Pangea was at its peak, stretching across the equator.

• Geography: The northern landmass was known as Laurasia, while the southern portion was Gondwana.

• Climate: The sheer size of Pangea caused massive seasonal swings and created harsh, dry interiors.

• Migration: Because the land was connected, new life forms could spread easily across the entire globe.

3. The Rise of New Giants

As the planet recovered from the Permian extinction, new groups of animals began to dominate the Sidmouth landscape:

• Therapsids: These mammal-like reptiles, such as the herbivorous Lystrosaurus, were common in the Early Triassic.

• Archosaurs: This group thrived and eventually gave rise to the first true dinosaurs during the Late Triassic.

• Early Dinosaurs: Unlike the giants of the Jurassic, these first dinosaurs were small and walked on two legs.

• Diversification: The Triassic also saw the first turtles, flying pterosaurs, and a wide variety of early insects and amphibians.