Cretaceous Period

The Cretaceous Period spanned 80 million years, lasting from 145 million to 66 million years ago. Following the Jurassic, this era saw the final breakup of the supercontinent Pangea, which created the continents and oceans we recognize today.

1. Local Geology: The Upper Greensand and Chalk

In the Sidmouth district, the Cretaceous is represented by two very different types of rock that form the high escarpments of the area.

• Upper Greensand: This is a glauconitic sandstone, often appearing as a yellowish-green layer at the top of hills like Peak Hill.

• The Chalk: A soft, white limestone formed from the microscopic remains of coccolithophores (single-celled marine algae).

• The Environment: Both formations were deposited in a warm, shallow sea that was teeming with marine life.

2. The Age of the Famous Giants

The Cretaceous is world-famous for being the peak of dinosaur evolution.

• Land Predators: The landscape was home to the apex predator Tyrannosaurus Rex and the nimble Velociraptor.

• Diverse Herbivores: Great herds of duck-billed Hadrosaurus, armored Ankylosaurus, and many others roamed the land.

• The Sea and Sky: While the land was dominated by dinosaurs, the oceans were ruled by fearsome marine reptiles like the Mosasaurus, and pterosaurs continued to dominate the skies.

3. A Changing World

This period wasn't just about giants; it was a time of massive biological and environmental shifts.

• Flowering Plants: The Cretaceous saw the rise of flowering plants, which revolutionized Earth's flora and provided new food sources that fueled a complex food web.

• Climate Shifts: The climate fluctuated, moving from warm and humid to cooler and drier toward the end of the period.

• Mammals: While small, mammals began to diversify during this time, preparing for their eventual dominance in the era to follow.

4. The Abrupt End: The Chicxulub Impact

The era of the dinosaurs came to a sudden halt 66 million years ago due to the Chicxulub asteroid impact.

• The Event: The impact triggered global wildfires, tsunamis, and extreme environmental changes.

• The Extinction: Approximately 75% of life on Earth was wiped out, including all non-avian dinosaurs.

• The Legacy: While devastating, this extinction allowed mammals to thrive and led to the diversification of life we see in the modern world.