What happened along the margin of the eastern United States during the Cretaceous Period?

The Cretaceous Period is the third and final epoch of the Mesozoic Era, lasting from approximately 145.5 million years ago (mya) to 65.5 mya. One of the most well-known events of this period is the mass extinction event at its end, resulting in the extinction of all non-avian dinosaurs. The continents were breaking apart, sea levels were rising dramatically, and the climate was generally warm and tropical.

During the Cretaceous Period, the Earth's continental plates experienced significant movement. The supercontinent of Gondwana had split and begun to separate during the Jurassic Period, with South America, Africa, Antarctica, and Australia gradually breaking apart. In the Cretaceous Period, the continents of Laurasia (modern-day North America, Europe, and Asia) and Gondwana drifted apart, ultimately forming the separate continents we know today.

The tectonic movement experienced during the Cretaceous Period led to the widening of the Atlantic Ocean. This is of particular importance to the eastern United States because it formed the margin adjacent to the ocean. The ocean's expansion resulted from eastward movement of North America, away from Eurasia and Africa, also causing the formation of a passive margin.

During the Cretaceous Period, several key geological events unfolded along the margin of the eastern United States: 1. Seaway Flooding: Dramatically rising sea levels led to the flooding of large portions of the continental shelf, creating an interior seaway extending from the present-day Gulf of Mexico to the Arctic Ocean. Coastal areas, like the eastern United States, significantly changed, with many habitable or largely terrestrial environments becoming shallow marine environments teeming with marine life. 2. Deposition of Sedimentary Rocks: The interior seaway allowed sediments from the eroding Appalachian Mountains to be transported and deposited in the eastern coastal plains. These sediments formed sedimentary rocks such as limestone, shale, and sandstone. 3. Formation of the Coastal Plain Province: The constant deposition of sediment created thick layers of sedimentary strata. These layers have formed the modern-day Coastal Plain Province in the eastern United States, which stretches from New York to Georgia.

During the Cretaceous Period, several geological events took place along the margin of the eastern United States, including the formation of the Atlantic Ocean, flooding of the continental shelf, deposition of sedimentary rocks, and formation of the Coastal Plain Province. These events shaped the modern-day landscape of the eastern US coast and impacted the evolution of diverse flora and fauna living in the region during that time.