About Isotopic Dating Yardsticks for Geologic Time

The work of geologists is to tell the true story of Earths history—more precisely, a story of Earths history that is ever truer. A hundred years ago, we had little idea of the storys length—we had no good yardstick for time. Today, with the help of isotopic dating methods, we can determine the ages of rocks nearly as well as we map the rocks themselves. For that, we can thank radioactivity, discovered at the turn of the last century. The Need for a Geologic Clock A hundred years ago, our ideas about the ages of rocks and the age of the Earth were vague. But obviously, rocks are very old things. Judging from the number of rocks there are, plus the imperceptible rates of the processes forming them—erosion, burial, fossilization, uplift—the geologic record must represent untold millions of years of time. It is that insight, first expressed in 1785, that made James Hutton the father of geology. So we knew about deep time, but exploring it was frustrating. For more than a hundred years the best method of arranging its history was the use of fossils or biostratigraphy. That only worked for sedimentary rocks and only some of those. Rocks of Precambrian age had only the rarest wisps of fossils. No one knew even how much of Earth history was unknown! We needed a more precise tool, some sort of clock, to begin to measure it. The Rise of Isotopic Dating In 1896, Henri Becquerels accidental discovery of radioactivity showed what might be possible. We learned that some elements undergo radioactive decay, spontaneously changing to another type of atom while giving off a burst of energy and particles. This process happens at a uniform rate, as steady as a clock, unaffected by ordinary temperatures or ordinary chemistry. The principle of using radioactive decay as a dating method is simple. Consider this analogy: a barbecue grill full of burning charcoal. The charcoal burns at a known rate, and if you measure how much charcoal is left and how much ash has formed, you can tell how long ago the grill was lit. The geologic equivalent of lighting the grill is the time at which a mineral grain solidified, whether that is long ago in an ancient granite or just today in a fresh lava flow. The solid mineral grain traps the radioactive atoms and their decay products, helping to ensure accurate results. Soon after radioactivity was discovered, experimenters published some trial dates of rocks. Realizing that the decay of uranium produces helium, Ernest Rutherford in 1905 determined an age for a piece of uranium ore by measuring the amount of helium trapped in it. Bertram Boltwood in 1907 used lead, the end-product of uranium decay, as a method to assess the age of the mineral uraninite in some ancient rocks. The results were spectacular but premature. The rocks appeared to be astonishingly old, ranging in age from 400 million to more than 2 billion years. But at the time, no one knew about isotopes. Once isotopes were explicated, during the 1910s, it became clear that radiometric dating methods were not ready for prime time.   With the discovery of isotopes, the dating problem went back to square one. For instance, the uranium-to-lead decay cascade is really two—uranium-235 decays to lead-207 and uranium-238 decays to lead-206, but the second process is nearly seven times slower. (That makes uranium-lead dating especially useful.) Some 200 other isotopes were discovered in the next decades; those that are radioactive then had their decay rates determined in painstaking lab experiments. By the 1940s, this fundamental knowledge and advances in instruments made it possible to start determining dates that mean something to geologists. But techniques are still advancing today because, with every step forward, a host of new scientific questions can be asked and answered. Methods of Isotopic Dating There are two main methods of isotopic dating. One detects and counts radioactive atoms through their radiation. The pioneers of radiocarbon dating used this method because carbon-14, the radioactive isotope of carbon, is very active, decaying with a half-life of just 5730 years. The first radiocarbon laboratories were built underground, using antique materials from before the 1940s era of radioactive contamination, with the aim of keeping background radiation low. Even so, it can take weeks of patient counting to get accurate results, especially in old samples in which very few radiocarbon atoms remain. This method is still in use for scarce, highly radioactive isotopes like carbon-14 and tritium (hydrogen-3). Most decay processes of geologic interest are too slow for decay-counting methods. The other method relies on actually counting the atoms of each isotope, not waiting for some of them to decay. This method is harder but more promising. It involves preparing samples and running them through a mass spectrometer, which sifts them atom by atom according to weight as neatly as one of those coin-sorting machines. For an example, consider the potassium-argon dating method. Atoms of potassium come in three isotopes. Potassium-39 and potassium-41 are stable, but potassium-40 undergoes a form of decay that turns it to argon-40 with a half-life of 1,277 million years. Thus the older a sample gets, the smaller the percentage of potassium-40, and conversely the greater the percentage of argon-40 relative to argon-36 and argon-38. Counting a few million atoms (easy with just micrograms of rock) yields dates that are quite good. Isotopic dating has underlain the whole century of progress we have made on Earths true history. And what happened in those billions of years? Thats enough time to fit all the geologic events we ever heard of, with billions left over. But with these dating tools, weve been busy mapping deep time, and the story is getting more accurate every year.

Guernica By Pablo Picasso And Executions Of Art - 879 Words

When comparing the two art pieces of art, â€Å"Guernica† by Pablo Picasso and â€Å"Executions of the Third of May† by Goya, you may interpret the underlying meaning to be the same. However, the era in which these paintings were created are noticeably different as well as the techniques. The history in which these two works were created is intriguing. The implicit and explicit similarities and differences between these two historical pieces are astonishing. â€Å"Guernica†, which was created in 1937 was Picasso’s reaction to the bombing of a Spanish city that the name of the work derived its name from. During the Spanish Civil War, Germany had supported the Nationalists side and provided them with weapons and other supplies, so when Adolf Hitler†¦show more content†¦A mother cries in agony while holding a small child in her arms, most likely one of the many victims who lost their lives. On the far right side of the painting, you can see a woman o n her knees, examining the skies as if she is expecting another bomb to fall from the sky. It is evident that her right leg is already injured. Violence and anguish is displayed in this famous piece of art. Francisco Goya was a Spanish Romanticist painter who was born 1746 and died in 1828. Although he was born near Saragossa, he was living in Madrid when he painted â€Å"Executions of the Third of May†. The famous painting refers to 1807 when Napoleon Bonaparte wanted to make an alliance with King Charles IV in order to conquer Portugal, but his true plan was to take over Madrid. When the French troops stormed Madrid, Napoleon claimed that they were just passing through, but when they began taking over, king Charles IV soon realized the alliance was a hoax. Soon after Napoleon’s brother, Joseph Bonaparte became the new king of Spain. The siege lasted three days and on the second day a rebellion broke out and on the third day, the rebels were slaughtered. It is said that Goya himself witnessed the murders from atop the hill of Principe Pio and once the massacre had ended he began making sketches of the bodies under his lantern. Although the story is not proven, it is clear that it affected him greatly. French soldiers stand in rows, aiming their rifles at what seems to be the focalShow MoreRelatedDifferences Between Modernism And Modernism1174 Words   |  5 Pagescreativity. The romantic period focused on the creativity of an individual’s art. However, after reading the two lectures, I believe the modernism period is when artists really started to discover innovative ways to create art. There were many artists in each genre of painting, composing, and poetry who had strong influences during the modernists period. The one artist who stuck out the most to me was Pablo Picasso. Pablo Picasso is one of the most well known artists of the modernism period. The modernismRead MoreThe Art of War: Goya and Picasso Essay1278 Words   |  6 PagesThe Art of War: Goya and Picasso War is hell. Literally. In an instant, in the blink of an eye, the world as we know it is torn apart and shredded. Normality explodes into atrocity as we see the depths of depravity that man can sink to. Even though their reasons for painting the pictures are different, Goya’s Third of May, 1808, and Picasso’s Guernica are testaments to the violence of war using specific events and symbolic features as their vehicle while their representations and styles areRead MoreLes Demoiselles DAvignon5704 Words   |  23 PagesLes Demoiselles dAvignon   Les Demoiselles dAvignon  (The Young Ladies of Avignon, and originally titled  The Brothel of Avignon) is a large  oil painting  of 1907 by the Spanish artist  Pablo Ruiz Picasso  (1881–1973). The work portrays five nude female prostitutes from a brothel on Avinyà ³ Street in  Barcelona. Each figure is depicted in a disconcerting confrontational manner and none are conventionally  feminine. The women appear as slightly menacing and rendered with angular and disjointed body shapesRead MoreArt History Study Guide3003 Words   |  13 PagesStephens/ Virgin and Child, Melun Diptych * Limbourg Brothers – Tres Riches Heures of the Duc de Berry * Flanders * Bosch, Hieronymus –Garden of Earthly Delights, Creation of Eve, Hell * Bouts, Dirk –Wrongful Execution of the Count; Justice of Otto III * Broederlam, Melchoir –Retable de Champmol Annunciation/Visitation/Presentation/ Flight to Egypt * Campin, Robert –Merode Altarpiece * Christus, Petrus –Goldsmith in his Shop Read MoreIwc1 Literature, Arts and Humanities Essay10028 Words   |  41 Pageseffect to cause). Question 5: Multiple Choice Why is architecture considered an art? a) Because architecture provides shelter to humans b) Because architecture is often decorated with art forms c) Because architects use perspective in their work d) Because architecture is concerned with the aesthetic effect of structures in their environment Feedback: The correct answer is d. Architecture is considered an art because it is concerned with the aesthetic effect of structures in their surrounding

Play in school Essay Example For Students

Play in school Essay There were different doors on the stage, the ones on stage left were poor and battered leading into council houses; this is where the Johnston family lived, the doors on stage right was hidden but the ones shown were new posh doors maybe leading into mansions. To show the Lyons house they used flying scenery; one wall flat of a house to show a living/dinning room. This also happened when the scene was in Mrs Johnstons kitchen. To show Mickey and Lindas house they rolled on another wall flat of a living room. The doors stayed on the stage for all of the play, the only time they changed is when the Johnston family moved to the countryside; they were still council but were in much better condition. A sort of raised platform this was used by the always-watching narrator who never left the stage, to watch, to enter and exit to a wing upstairs, it led to were the orchestra were.  Only a few scenes changed throughout the play but most of the time to change the scene the stage were just striked. The biggest scene change was when the scene changed from the street houses to the countryside, the backdrop changed here also from the houses and factories of the city to the farms and fields of the countryside. This took place during the interval. Sound and music were also used to display the emotions in each scene. The type of sound was mainly special effects for things like thunder when Mrs Lyons went insane and birds tweeting in the country scene.  The orchestra also contributed to the sound before and during the play, it was nothing too evident, which did not really give much of an impact, which is a good thing.  The Music during the play was very harsh and the pace was always fast, the songs were very hum able and catchy but I believed that the played Marilyn Monroe and shoes upon the table a bit too much as they started to get a bit annoying after a while During the play, the stage was lit using foot lights and floodlights, which made it quite bright. The only times when the scene was not light was either when the effect of night was wanted or when Mrs. Lyon was going insane and flashing lights with blue gels were used, also a tree or flame was shown on the stage using a shadow.  There was a few times in which light effects were used, for example when there were blackouts to show the years gone past, flashing lights were also used to show different shops and arcades in the carnival when Linda, Mickey and Eddie were growing up. This was effective, and was an amazing contrast compared to the scene with Mrs Lyons, which had a completely different mood that was well conveyed by the lighting used in both scenes. The play would not have been as good if only the house lights were used. The costumes in the play reflected the character and his or her personality well. When they were children Mickey wears torn shorts and T-shirt that do not fit him properly, Eddie wears shorts, a shirt and a jumper and white knee high socks that were always clean and tidy. As they get older they stop wearing shorts and start to wear jeans and jumpers when finally they grow up to show their maturity they wear jeans, shirts and blazers. Not only do the costumes show the age changes but also the difference in class; Eddie would wear designer, posh clean clothes all the way through the play while Eddie would wear standard middle class clothes .u27677b13a3256320d10e6604778ffc8f , .u27677b13a3256320d10e6604778ffc8f .postImageUrl , .u27677b13a3256320d10e6604778ffc8f .centered-text-area { min-height: 80px; position: relative; } .u27677b13a3256320d10e6604778ffc8f , .u27677b13a3256320d10e6604778ffc8f:hover , .u27677b13a3256320d10e6604778ffc8f:visited , .u27677b13a3256320d10e6604778ffc8f:active { border:0!important; } .u27677b13a3256320d10e6604778ffc8f .clearfix:after { content: ""; display: table; clear: both; } .u27677b13a3256320d10e6604778ffc8f { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .u27677b13a3256320d10e6604778ffc8f:active , .u27677b13a3256320d10e6604778ffc8f:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .u27677b13a3256320d10e6604778ffc8f .centered-text-area { width: 100%; position: relative ; } .u27677b13a3256320d10e6604778ffc8f .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .u27677b13a3256320d10e6604778ffc8f .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .u27677b13a3256320d10e6604778ffc8f .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .u27677b13a3256320d10e6604778ffc8f:hover .ctaButton { background-color: #34495E!important; } .u27677b13a3256320d10e6604778ffc8f .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .u27677b13a3256320d10e6604778ffc8f .u27677b13a3256320d10e6604778ffc8f-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .u27677b13a3256320d10e6604778ffc8f:after { content: ""; display: block; clear: both; } READ: Physical Therapy EssayIt was the first time that I saw Blood Brothers and I understood the play to a certain extent but not as fully as the other people did because I am not studying the play in school.  Although the production is a brilliant one, I thought that the actors playing the characters of Mrs. Lyons and Mrs Johnston was not thought out enough and turned out to be characterless and bland. An example of this is when Mrs Lyons appears in Mrs Johnstons home and threatens her, the struggle between the two ended up to be a bit pathetic. The characters of Mickey and Linda were a lot better, they were exciting and competent, they also were able to show their characters development well through out the play. My favourite character in the play was Mickey. Mickeys character was the one that in my opinion was more developed, the one that stood out from the other main characters and the best acted. I also liked the way that his character gradually changed through out the play and not many actors can carry it out as well as he did. The change of Mickeys character was obvious during the play but the actors change was not. Apart from Mrs Lyon and Mrs Johnston, I believe the choice of cast was very well done. It is my favourite play, so far because it is filled with humour, Romance, attraction and physical humour.  As a whole, I thought the audience really enjoyed the performance and I liked the way the director slipped in a few jokes.  Along with the tears, this compelling and heart-wrenching story of the Liverpool working class mum, pressured into giving away one of her newborn twins at birth so that he can have a better life, also has warmth, tenderness, love and laughter

Lord of the Flies

Lord of the Flies- Fear is the Source of All Evil Essay The Lord of the Flies is all about fear. Golding seems to be suggesting that fear, and its complications are the source of all evil. Throughout the novel, the boys show fear in many things. They see and hear assorted things on the island and assume them to be beasts to be dreaded. After much disorder and turmoil on the island, a group of hunters offer a gift to the much sought after and feared beast. A young boy, who is not a part of the group of hunters, encounters their gift to the feared beast and he even talked to it, learning the causes of all the evil on the island. The boy attempts to share his discovery in an attempt to end the fear of the beast and to halt the evil on the island. Sadly, he is mistaken for the dreaded beast that apparently inhabits the island. The hunters, in fear, savagely, murder Simon, ending all ones hopes for the end of evil. By the end of the novel, all the boys, except for Ralph have regressed into a primitive state and have lost all morals, until thei r rescue, when they finally see how bad they have been. The plot of this novel is based on fear, fear that leads to evil. In Beast from the Water, fear spreads through the group. Ralph, the current leader of the group, tries to convince the boys that their fear of a beast is absurd. Ralph is unsuccessful in deterring the fear of the boys. Several of them tell of monsters they have heard of, like the giant squid, and ponder the fact that beasts and ghosts may be roaming the island. Ralph observes all this and is powerless to control the situation. He calls a vote to decide if the ghosts are real. This is the climax of a series of futile attempts to hinder their fear. The sanity that is left among the boys is disappearing rapidly. The fear of the beasts is only growing more serious. In a group meeting, Simon tries to tell the boys that if there is a beast to fear, it exists within their own hearts. His attempts are futile as the boys simply laugh at him. The meeting soon turns chaotic due to Jacks defiance of Ralphs rules and the boys run off, led by Jack. The boys minds are still occupied with thoughts of beasts roaming the island. Ralph is still on his mission to end their fear in beasts. Jack, Ralph and Roger climb a hill late at night while searching for beasts. They see do see a beast. It is really a dead man who is suspended by his parachute. They boys only see his silhouette and they hear a flapping noise caused by the wind blowing against his equipment. The three boys run in fear. Now, even Ralph is frightened. Jacks new group fear the beast so much that they leave a gift for the beast. They took head of a hunted pig, mounted it on a pole and left it standing in the jungle. This head becomes a symbol of terror. Even the boys that put the head there became frightened and ran away because of it. Simon has been sitting alone in the jungle, starting at the fly-covered head of the dead pig as if he was in a trance. The heat becomes intense and the air is humi d and close, due to a brewing tropical storm. Suddenly, it seems as if the head the Lord of the Flies is speaking to him. It warns Simon that it is impossible to escape him, the beast, for he is a part of everyone, and he is responsible for all the difficulties that they are facing. The Lord of the Flies is explaining that there is no sense in trying to hunt and kill the beast. You knew didnt you? Im a part of you Close, close, close! Im the reason why its no go? Why things are they way they are? The Lord of the Flies answers the question of why the civilization of the boys is a failure. The destructive element is in the boys themselves in each boy. The tittle of the head, Lord of the Flies, is a literal translation of the word Beelzebub, the name of a devil in the Bible. The Lord of the Flies is a very important symbol in the novel. It is fear unleashed. The pigs head represents the evil of unreason. The files that buzz over the intestines of the sow are instinctive beings, and the y represent the primitive urges that are beginning to dominate the boys. It is the destiny of the boys if they do not eliminate their fear of beasts beasts that are really in themselves. .u08a91ab0c86f1a3b619aed78a5cbed75 , .u08a91ab0c86f1a3b619aed78a5cbed75 .postImageUrl , .u08a91ab0c86f1a3b619aed78a5cbed75 .centered-text-area { min-height: 80px; position: relative; } .u08a91ab0c86f1a3b619aed78a5cbed75 , .u08a91ab0c86f1a3b619aed78a5cbed75:hover , .u08a91ab0c86f1a3b619aed78a5cbed75:visited , .u08a91ab0c86f1a3b619aed78a5cbed75:active { border:0!important; } .u08a91ab0c86f1a3b619aed78a5cbed75 .clearfix:after { content: ""; display: table; clear: both; } .u08a91ab0c86f1a3b619aed78a5cbed75 { display: block; transition: background-color 250ms; webkit-transition: background-color 250ms; width: 100%; opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #95A5A6; } .u08a91ab0c86f1a3b619aed78a5cbed75:active , .u08a91ab0c86f1a3b619aed78a5cbed75:hover { opacity: 1; transition: opacity 250ms; webkit-transition: opacity 250ms; background-color: #2C3E50; } .u08a91ab0c86f1a3b619aed78a5cbed75 .centered-text-area { width: 100%; position: relative ; } .u08a91ab0c86f1a3b619aed78a5cbed75 .ctaText { border-bottom: 0 solid #fff; color: #2980B9; font-size: 16px; font-weight: bold; margin: 0; padding: 0; text-decoration: underline; } .u08a91ab0c86f1a3b619aed78a5cbed75 .postTitle { color: #FFFFFF; font-size: 16px; font-weight: 600; margin: 0; padding: 0; width: 100%; } .u08a91ab0c86f1a3b619aed78a5cbed75 .ctaButton { background-color: #7F8C8D!important; color: #2980B9; border: none; border-radius: 3px; box-shadow: none; font-size: 14px; font-weight: bold; line-height: 26px; moz-border-radius: 3px; text-align: center; text-decoration: none; text-shadow: none; width: 80px; min-height: 80px; background: url(https://artscolumbia.org/wp-content/plugins/intelly-related-posts/assets/images/simple-arrow.png)no-repeat; position: absolute; right: 0; top: 0; } .u08a91ab0c86f1a3b619aed78a5cbed75:hover .ctaButton { background-color: #34495E!important; } .u08a91ab0c86f1a3b619aed78a5cbed75 .centered-text { display: table; height: 80px; padding-left : 18px; top: 0; } .u08a91ab0c86f1a3b619aed78a5cbed75 .u08a91ab0c86f1a3b619aed78a5cbed75-content { display: table-cell; margin: 0; padding: 0; padding-right: 108px; position: relative; vertical-align: middle; width: 100%; } .u08a91ab0c86f1a3b619aed78a5cbed75:after { content: ""; display: block; clear: both; } READ: 12 Angry Men Essay After Simons encounter with the Lord of the Flies, he wanders off, despite his fear and fatigue. He crawls up a hill and immediately discovers the cause of all the terror on the island. He sees the dead pilot entangled in some rocks and flapping in the breeze. Simon staggers off to inform the other boys of what he has learned. Meanwhile, Jack is holding a banquet that everybody is attending, including Ralph and Piggy. Suddenly, a black shape is seen crawling from the jungle, waving and calling to them. It is Simon with his message. The Beast! the frenzied boys shout, Kill the Beast! In their fear, they failed to recognized that it was Simon. The crazed boys of Jacks tribe leap upon him, beating and tearing him to death, despite his cries of pain and terror. Simons message never becomes revealed. He is the only one who understands the nature of evil on the island. Therefore, he is a threat to the continuance of that evil, and so, that evil must destroy him. Simons death leads to the s avages turning their violence to Piggy and Ralph. Jack soon steals Piggys glasses which foreshadows his inevitable death. Without glasses, Piggy cannot see, therefore loosing all knowledge. Roger tries to kill Piggy by rolling a huge boulder at him, trying to kill him in his futile attempts to get his glasses back. Piggy hears the boulder, but he cannot see where it is coming from. Piggy and the conch are crushed beneath it. With Piggy dead, and the conch broken, Ralph has no hope of becoming the leader again. Without Ralph as the leader, the boys will remain in primitive disorder and chaos. The hope of Ralph regaining power ends, along with the hope of the hunters overcoming the beast. Ralph, being the only one that has not joined Jacks tribe, is feared somewhat and is being hunted down. Jacks tribe has many forms of torture awaiting Ralph on his capture. While the boys are chasing Ralph, he collapsed in exhaustion, but when he looked up he saw a naval officer standing before him. Ralph is finally free from the terror and the evil of the island. The naval officer is shocked that several boys have been killed and that all traces of civilization have disappeared. The boys begin to cry. The naval officer turns his back and contemplates the sight of his cruiser in which he is sent out to do something as primitive as killing and destroying. Golding seems to be suggesting that fear, and its complications, is the source of all evil. It caused the majority of the boys to commit unspeakable acts of violence and immorality. Ralphs phrase, the darkness of mans heart. vividly describes his feelings of shame and confusion of how the others could be so bad. At the end of the novel, he cries for the end of innocenceand the fall through the air of the true, wise friend called Piggy. Their fears were rooted in beasts throughout the novel. This led the boys offering a gift to this beast, and innocent boys being murdered. Category: English