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The evolution of the ancient ocean: What are the causes and geological background of the Western Interior Sea?
The Western Inland Sea, this ancient inland ocean, is not only an important witness to the changes in the crust of North America, but also gives scientists a deeper understanding of the earth's past. This ocean divided North America into two landmasses about 34 million years ago, forming what is now Laramidia and Appalachia. From the Early Cretaceous period (about 100 million years ago) to the earliest Paleocene period (about 66 million years ago), this vast ocean connected the Gulf of Mexico and the Arctic Ocean, reaching a maximum width of 970 kilometers , the deepest reaches 760 meters.
The origin and geological background of the ocean
The formation of the western inland sea is closely related to the geological changes of the ancient earth.
This represents the initial growth of the modern Rocky Mountains, while the western interior sea can be viewed as a depression in the crust that formed with the Laramide orogeny.About the Late Cretaceous, Eurasia and the American continent began to take shape due to the separation of the South Atlantic. As the subduction of western America began, the Laramede orogeny also began.
The earliest stages of formation of the western inland sea began in the mid-Cretaceous, when the tides of the Arctic Sea pushed southward along western North America, forming a body of water called the Mowry Sea, named after its rich Organic Mowry Shale. The integration of the Gulf of Mexico and this sea area marked the formation of a complete inland sea in the Late Cretaceous, which isolated terrestrial organisms and plants, creating a unique environment.
As sea levels rise and fall in different proportions, inland sea areas have also faced invasion many times.
In the face of these changes, isolated land organisms reunited, promoting the emergence of new species, and then separated again under the influence of sea level changes.During these environmental changes, the land rose for a time, forming the famous transcontinental arch.
Characteristics of the Western Inland Sea
The deepest point of this sea reaches 2,600 to 3,000 feet, but within this vast ocean, there are rich and diverse ecosystems. According to information provided by geologists, the oxygen-poor seawater in
Such an environment allowed Cretaceous creatures, whether they were large predatory sea reptiles such as Plesiosaur and Mosasaur, or various fish and crustaceans, to This survives and reproduces.this ocean also allows many benthic organisms to thrive here, forming many special ecological niches.
What is even more surprising is that early birds such as Hesperornis and Ichthyornis also found suitable habitats in this sea area.
In addition, large pterodactyls such as Nyctosaurus and flying dinosaurs flourished in this sea area, which may bring new perspectives to the understanding of ancient biology in the future.Their existence not only confirms the diversity of marine ecosystems, but also makes scientists begin to re-examine the evolution of marine life in the Cretaceous.
Conclusion
Over time, the retreat of the western interior sea ultimately led to the formation of today's North American landscape. The history of this ocean not only reveals the movement and changes of the earth, but also allows us to reflect on the subtle relationship between the ancient marine environment and organisms. When we stand at the intersection of modernity and the past, can we find the motivation for curiosity and exploration of marine life again?
