Cretaceous-Paleogene Boundary Essay

Large amounts of iridium – a chemical element that is not a part of the Earth’s crust composition – were originally found in rocks of Europe and United States, and have been found everywhere ever since. Iridium, common in meteorites, is a testable evidence of the disaster hypothesis. Gould continues that the Cretaceous debacle, which is one of five episodes of mass dying, occurred at the same time as the large comet might have smashed into the Earth. The author believes this is not merely a coincidence, rather, it is a proof of the cause-effect relationship. The demise of a wide range of habitats along with the extinction of dinosaurs gives an inestimable advantage to the disaster theory over other claims, the author adds. The comet struck the Earth, and habitats, from terrestrial to marine, died with geological suddenness. Finally, this hypothesis has had an impact on the study of an atomic war and its consequences. A nuclear war, Gould says, may cause a huge drop in temperatures and result in the extinction of humanity. Testable evidence, study, development, contribution – all this makes good science.

Gerta Keller, professor of geosciences at Princeton University, has recently conducted research on the Chicxulub asteroid in which she analyzed new core samples taken from the asteroid site (Botzer 2004). These samples indicate that the impact that occurred at Chicxulub actually predated the mass extinction of the dinosaurs, which occurred at the Cretaceous-Tertiary boundary about sixty-five million years ago. Keller claims that the Chicxulub impact occurred approximately 300,000 years before the extinction (Keller 2004). Although previous researchers estimated that the Chicxulub asteroid was the cause of the extinctions, there had always been doubts about the exact age and size of the crater, and about the origin of the “mega tsunami deposits” that were located within the crater (Keller 2004). The focus of Keller’s recent research was on finding some answers to these questions. To do so she analyzed Cretaceous limestone, dolomite, and anhydrite deposits as the site of the Chicxulub crater (Keller 2004).

The Chicxulub crater is located on Mexico’s Yucatan peninsula and evaded detection for decades because it was buried while at the same time being reserved beneath a kilometre of younger rocks and sediments. Most scientists now agree that the Chicxulub crater is evidence that a huge asteroid or comet crashed into the Earth's surface 65 million years ago causing the extinction of more than 70% of the living species on the planet, including the dinosaurs. This collision idea was first popularised in 1980 by Luis Alvarez and his son, Walter Alvarez, where they developed the Alvarez hypothesis. They were studying a one centimetre-thick layer in Italy, which

He narrowed his hunt down to a location in Denmark, where he had sent a colleague to perform an iridium analysis test at ("Asteroids and Dinosaurs: Unexpected Twists and an Unfinished Story," n.d.). When the results came back, Alvarez knew that whatever happened had not been a small-scale disaster. Once again, Alvarez was back to asking questions. What caused the increased iridium levels at the KT boundary? Except this time, he realized that his observations supported the ten year old hypothesis that had been proposed by paleontologist Dale Russell and physicist Wallace Tucker ("Asteroids and Dinosaurs: Unexpected Twists and an Unfinished Story," n.d.). They brought up the possibility of a supernova being the cause of dinosaur extinction. Supernovas are known to release high amounts of iridium, so such a hypothesis fit perfectly with Alvarez’s team’s discovery. However, the hope of having found a conclusion was short-lived. Luis Alvarez had mentioned that if said supernova had occurred that it would have released amounts of plutonium which would have been found alongside the iridium; no plutonium was found at either site. After more digging, the team came up with a new hypothesis ("Asteroids and Dinosaurs: Unexpected Twists and an Unfinished Story," n.d.). Perhaps an asteroid had struck Earth towards the end of the Cretaceous period, blowing enough dust into the atmosphere to

On the first side of the outcrop the rock when examined was greenish and had small black grains indicative of diorite with hornblende giving the green color. The rock was similar to the outcrop encountered at Hollow rock which also had several fractures parallel although not as many, and that outcrop was also highly weathered. On the other side of the outcrop, the rock was incredibly different. This side was not weathered beyond recognition but

The sedimentary layers of rock and soil are used by the evolutionists to argue that the layers of rock would have gradually built up over millions of years. Paul D. Ackerman in his book, It’s a Young World After All: Exciting Evidences for Recent Creation, argues that if it took millions of years to build the rock layers found in the Grand Canyon, then scientists should be able to encounter countless numbers of meteors. “With the passage of vast amounts of evolutionary time, these accumulating meteorites would be incorporated into the geologic column, and there should be many of them contained in the rock layers today.” Geologists should be coming across chunks or at least pieces of meteors when digging or observing the layers. However, they do not; which means that there must have been a catastrophic event that laid down the geologic column quickly. This would explain why there are not any indications of meteors in the geological column. Ackerman ends the chapter with a clear cut conclusion: “What do the data show? A clear result in favor of a recent creation. One survey of the literature a few years ago failed to turn up a single case of a meteorite being found in the geologic column. The meteorite clock reads clearly to the effect that the earth is not very old.”

There was much speculation regarding the K/T boundary being caused by a meteorite. The impact of this event was believed to have led to extended volcanic activity periods that in turn further polluted the atmosphere. The impact of the K-T boundary happened to be attributed to the extinction of dinosaurs that might have been as a result of new diseases. The impact affected all living things including primates. The impact is believed to have drastically slowed primate evolution (Clyde, 2010).

The beginning of the Jurassic brought a new climate. The weather changed from arid, dry, and seasonal to humid, hot, and stable. The weather allowed for lush jungles to flourish, and with the lush jungles, the dinosaurs. The weather change was due to the supercontinent Pangea breaking apart. Two new smaller supercontinents were formed, Gondwana and Laurasia. The supercontinents now had more area that was touching the ocean. This meant the water from the ocean made the supercontinents more humid than before. The dinosaurs thrived in this climate. New species are being discovered to this day from the Jurassic Period due to the immense diversity amongst them.

The skeletal characteristics of these hominines suggest that their mode of locomotion was likely a cross between occasional bipedalism and obligate bipedalism. From the reading we have learned that obligate bipedalism is bipedal locomotion that is practiced all of the time while occasional bipedalism is bipedalism that is practiced on occasion. The ratio of arm length to leg length (longer arms) suggests that they did spend time climbing trees, however the cranial and post cranial traits of these fossils suggest that they spent much of their time on the ground and likely ambulating bipedally combined with a variation of upright walking and knuckle walking. This is evidenced by two factors: the fact the foramen magnum of the skull is centrally located, and the ratio of arm to leg length. In creatures with bipedal ambulation, the foramen magnum is located in the center of the base of the skull to keep the head aligned over the center of gravity of the creature. If the fossils were walking primarily with their knuckles, the

The western Cordilleran orogenic belt had been depicted as a passive margin after Neoproterozoic to Early Cambrian rifting. Afterwards, the passive margin converted to an active margin most probably about Late Devonian to Late Cretaceous through the subduction of the exotic allochthons beneath the North American plate. The late Jurassic to Cretaceous subduction of (Sevier and Laramide Orogeny) representing as a period of the back thrust, intraplate thrusting, behind a magmatic arc on the upper plate near or on its westernmost margin from the latest

In the eastern part of the plateau most of the carbonate strata is Fredericksburg and Washita rock (Barker and Ardis 1996, 5). The plateau is dominated by a flat undistinguished plain, with the exception of the caprock mesas, the broad alluvial fans and the Balcones fault zone (Barker and Ardis 1996, 5). During the Paleozoic era the Ouachita Orogeny tectonic event occurred depositing marine sea deposits of upper Permian sediments and evaporates into the Permian basin, which is above parts of the Edwards-Trinity plateau aquifer (Anaya 2001, 107). Another prominent structural feature is the Llano uplift which is comprised of Precambrian rock mostly granite, located in the northern Hill Country area (Anaya 2001, 107). The Balcones fault zone was created from tensional stress from the uplift and deposition of sediments into the Gulf of Mexico, along the Ouachita belt, forming the faults by displacing the sediment 900 to 1200 feet (Anaya 2001, 109). The Edwards-Trinity plateau has two regional confining layers, Navarro-Del Rio, which confines the Edwards aquifer, and the Hammett that confines the Trinity and the Edward-Trinity aquifers (Barker and Ardis 1996, 2). The Navarro-Del Rio confining unit is regionally continuous within the Balcones Fault Zone; it is comprised of Buda limestone, Navarro Group,

Assess the different hypotheses put forward for the mass extinctions at the end of the Permian and Cretaceous (KT) Periods.

According to the research made by Alvarez (1980), it was due to an asteroid impact that single-handedly destroyed dinosaurs to extinction. Advocacy of this mechanism has been aided by the availability and tangibility of supporting evidence in the form of impact craters- the Chicxulub crater in the Yucatan Peninsula's date and timing of impact (dating produced an almost exact date of 65 million years ago), location, enormous size-170 km (Hildebrand et al.1991) and its high iridium content ( a metal not commonly found at the Earth's surface) make it seem that with a theoretical asteroid 10 km big caused the crater great damage at the end of the Cretaceous (Alvarez et al. 1980).

Over 98% of all organisms that have lived on Earth are now extinct. A mass extinction event occurs when a large number of species die out within a small time frame (relative to the age of Earth). Mass extinctions are intensively studied for both cause and effect, as there is usually room for debate regarding catalysts that precede the extinction and the massive influx of new biological species that follows. There have been five major mass extinctions, dubbed the “Big Five,” that have wiped out at least 50% of the species living at those times. The most well known mass extinction of the Big Five, with the decimation of every species of non-avian dinosaur, is the Cretaceous-Paleogene

These techniques led to the discovery of the boundary between the two eras. A single thin layer of clay found within predominantly limestone rocks established this. By comparing the marine life found in, above, and below the clay, the marine life, like the dinosaurs, had been terribly affected by the extinction event. The percentage of life in the upper layers was dramatically lower than that in the lower. This was far more compelling than what was suggested by dinosaur’s fossils.