The Cretaceous-Tertiary Impact Theory

Introduction The Cretaceous- Tertiary defunctness event was one of the largest toilet extinctions constantly recorded on Earth. Occurring 65 million eld ago, this cataclysmal event marked the extinction of thousands of animal species including dinosaurs, mosasaurs, plesiosaurs, and pterosaurs. spectacular extinctions withal occurred among microscopic floating organisms; both chalky plankton and calcareous nanoplankton were close exterminated with only a few species live on (Alvarez et al. 1980). Alternatively, well-nigh groups were unforesightful affected, including the terrestrial plants, crocodiles, snakes, mammals, and many kinds of invertebrates. It is estimated that a little e very(prenominal)place half of all living species depict at the balance of the Cretaceous did not survive the mass extinction (Russell 1979). A dark grey clay sediment point 3-8 centimeters cryptic divides the end of the Cretaceous period and the beginning of the Tertiary, this laye r is referred to as the K-T boundary and is found nearly globally (K is the traditional abridgment for the Cretaceous Period, and T is the abbreviation for the Tertiary Period). For years the scientific community debated the cause the extinction; many hypotheses, such(prenominal) as massive volcanic eruptions, excessive solar shaft and others, were presented however they lacked the proper supporting evidence.

Finally, beginning in the 1980s through until the early 1990s several prominent researchers including Luis Alvarez, Bruce Bohor, and Alan Hildebrand began to present evidentiary proof that an asteroid impact caused the Cretaceous-Tertiary (K-T) ! mass extinction. In this motif we will discuss the Cretaceous-Tertiary Impact theory and await at the important pieces of evidence supporting it, including the high levels of iridium and blow out of the water quartz in the K-T layers, as well as the Chicxulub crater in southern Mexico. atomic number 77 concentrations Iridium is an element of the platinum group of metals; it is very hard, very dense and is one of the rarest...If you essential to get a unspoilt essay, order it on our website: BestEssayCheap.com

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