The NASA Earth Observatory website published an article at the end of October 2021 by Sara E. Pratt, referring to the limestone sediments that swirl off the Yucatan Peninsula.
(NASA).- MÉRIDA, Yucatán.- In NASA’s Twitter account, the article by Sara E. Pratt was shared with an image of the Yucatan Peninsula with the title: “Limestone suspended in the hints of the high sea at a history of 66 million years”.
The asteroid that extinguished the dinosaurs fell in Yucatan 66 million years ago
The article indicates that 66 million years ago, an asteroid or comet about 14 kilometers (9.5 miles) wide crashed into Earth, making a direct hit on what is today the coast of the Yucatan Peninsula, which back then was at the bottom of a shallow sea. The impact was catastrophic. It triggered tsunamis, caused wildfires, and ejected a cloud of ash and dust that circled the globe, blocking out the Sun and cooling the climate. The collision and its aftermath wiped out 75% of all life on Earth, including the dinosaurs.
What is the Chicxulub crater like?
Following the description of the cataclysm, the article by Sara E. Pratt refers to the 180-kilometer-wide crater near the town of Chicxulub, on the north coast of the Yucatan peninsula. The writer describes the location of the city of Mérida, which is inland south of Chicxulub, on the map, noting that it appears as a grayish-brown area near the top of the image, which was generated by the spectroradiometer of Moderate Resolution Imaging (Modis) on NASA’s Terra satellite on October 31, 2021.
In her article, Pratt points out that Chicxulub is the best-preserved large impact crater on Earth. In the millions of years since the impact, the crater has been buried. However, the remains of this crater are still visible on the surface.
The author explains that a 250-kilometer arch of sinkholes, or cenotes, marks the rim of the crater, which provided fresh water to the ancient Maya inhabitants of the peninsula. Because rainwater is slightly acidic, surface water dissolves and percolates through the limestone bedrock, creating cenotes, underwater caves, as well as the longest underground river in the world.
She also points out that when limestone layers erode, calcareous sediments are washed into the broad, shallow Yucatan shelf. Pratt returns to the image description and notes that sediment eddies are visible off the north and west coast of the Bay of Campeche.
The author also adds that sediments scatter light and this reflectivity gives water its characteristic color when viewed from space. When it floats near the surface, the sediment appears dark brown, but as it sinks and disperses, the color changes to shades of green and light blue.
When shallow coastal waters are stirred up by winds, tides, storms, or currents, sediments on the seafloor can be resuspended, causing seawater to appear white or pale blue. Some of the colors may also come from phytoplankton, which sometimes floats to the surface in blooms large enough to be seen from space.
The date of the impact of the asteroid in Yucatan
At that time, a study led by a Florida Atlantic University (FAU) research team was also released that has conclusively determined the time of year when the asteroid collided with Earth and affected the evolution of the Earth. life on the planet.
According to the study, the asteroid fell in Chicxulub in the spring of that time, 66 million years ago.
Using radiometric dating, stratigraphy, fossil pollen, fossils, and iridium-rich clay topsoil obtained from the Tanis site in southwestern North Dakota, United States, one of the most detailed Cretaceous and Paleogene frontier sites in the world, the researchers corroborated the impact information.