Continental Configuration and Seaway: During the early Cretaceous, the Atlantic Ocean continued to widen as the process of continental breakup persisted. The Western Interior Seaway, a vast inland sea, extended across North America, dividing the continent into eastern and western landmasses.
Flourishing Dinosaurs and Terrestrial Ecosystems: The Cretaceous is renowned for the diversity of dinosaurs, including the massive sauropods and the famous Tyrannosaurus rex. Flowering plants (angiosperms) further transformed terrestrial ecosystems, providing food sources for both herbivorous and carnivorous dinosaurs.
Chalk Formation and White Cliffs of Dover: During the Cretaceous, the deposition of calcium carbonate-rich sediments led to the formation of chalk deposits. The iconic White Cliffs of Dover in England are composed of Cretaceous chalk, created by the accumulation of microorganisms’ skeletons called coccolithophores.
Tectonic Activity and Mountain Building: The movement of tectonic plates during the Cretaceous resulted in the formation of mountain ranges. The Rocky Mountains in North America and the Andes in South America are examples of ranges that formed or were modified during this period.
Extinction of Dinosaurs and Chicxulub Impact: The Cretaceous concluded with a mass extinction event caused by the impact of a massive asteroid near the Yucatán Peninsula in present-day Mexico. The impact, known as the Chicxulub impact, led to the extinction of non-avian dinosaurs and many other species.
Sedimentary Rocks and Fossils: Cretaceous rocks consist of various sedimentary deposits, including sandstones, shales, and limestones. Fossilized remains of marine organisms, dinosaurs, plants, and insects are commonly found in these rocks.
Tropical Climate and Eustatic Changes: The Cretaceous climate was generally warm, with high atmospheric carbon dioxide levels. Sea levels experienced fluctuations due to eustatic changes, resulting in the formation of different marine environments.
Mineral Resources and Economic Significance: Cretaceous rocks are associated with the formation of various mineral resources, including oil and natural gas. These resources have been of economic importance to human societies. In summary, the Cretaceous Period is characterized by the continued evolution of diverse ecosystems, the dominance of dinosaurs, significant geological events, and the catastrophic Chicxulub impact that concluded the era. The geological and biological changes during the Cretaceous laid the groundwork for the modern world we see today.