Northern Ireland with if conditional type 1

The Revolt of the Northern Earls (1569) Most people in the North remained loyal to the Catholic noble families who controlled the north and their Catholic faith. When Elizabeth came to power, she promoted ‘new men’ (Protestants) from the gentry and the powerful Catholic nobles lost their power and influence. This led them to organise the most serious rebellion of Elizabeth’s reign in 1569. Why did the Northern Earl’s revolt? The Earls had lost their power when Elizabeth became Queen (and wanted it back). They wanted Catholicism restored in England (and felt that ordinary Catholics would support it). Elizabeth was refusing to marry or to name an heir, causing uncertainty about England’s future. Mary Queen of Scots (if freed from prison) could replace Elizabeth and solve all these problems Who were the key players in the Revolt? Earl of Northumberland • A Catholic who had held an important position under Mary I. • He lost a lot of influence under Elizabeth (as she favoured Protestant gentry) • Elizabeth also took the rights to a valuable copper mine found on his lands Earl of Westmorland • From a rich Catholic family in the north Also the Duke of Norfolk’s brother in law Duke of Norfolk • England’s most senior Protestant noble, but he had very close links to old northern Catholic families, & was sympathetic to them & greedy for power. • He hated William Cecil & Robert Dudley, Earl of Leicester (Elizabeth’s favourite) who were Protestant and from the gentry • He planned to marry Mary QS, but later backed down and urged the earls to call off the rebellion. Mary also supported the plan to marry him What role did religion play? (7/10 – but only because it was linked to power) • Most northerners held onto their Catholic beliefs & although Elizabeth didn’t persecute them, they knew that she wanted their religion to gradually die out, so they supported the revolt. • In 1561 Elizabeth hired a strict Protestant as archbishop of Durham to promote Protestantism in the north, but he was unpopular & turned many northerners against the Protestant religion. What role did politics/power play? (9/10 – this was the most important cause of the revolt) • The Northern Earls lost a lot of their power/influence (even jobs/money under Elizabeth) • Northumberland was jealous of new Protestant families being given top jobs in the North • William Cecil & Robert Dudley were not from ancient noble families, but were very close to the Queen, so the northern Earls resented them getting top jobs in her Government • Elizabeth also confiscated large areas of land & the profits from their copper mines • It is possible, that had Elizabeth allowed the Catholic Northern Earls to keep their jobs, money and influence at court, they may have ‘tolerated’ her as a Protestant Queen (greedy/selfish). What role did Mary Queen of Scots and the Succession play? • Elizabeth was refusing to name an heir and it was becoming clear that she would not marry • If Mary Queen of Scots married the Duke of Norfolk, England would have an heir and England would be Catholic again. The country would be stable without people competing for power. • However, some of Elizabeth’s courtiers got worried that it might not work and that it might lead to charges of treason (punishable by death) • So by September 1569, Robert Dudley (Earl of Leicester) decided to tell Elizabeth about the plot. By this time it was much more serious than simply marrying Norfolk to Mary. • Mary QS had secretly asked Spain to send troops to help the rebellion & overthrow Elizabeth Plan for the Revolt of the Northern Earls (1569) • The Earls of Northumberland & Westmorland will raise rebel troops from their lands in the north and take control of Durham. • The rebels will then march south towards London to join with the Duke of Norfolk • 1000s of Spanish troops will land in England to support the rebel forces • The Duke of Norfolk & rebel forces will seize control of Government & overthrow Elizabeth • Mary Queen of Scots is to be freed, ready to marry the Duke of Norfolk Key Events of the Revolt • Once Elizabeth knew of the plot, Norfolk was arrested and sent to the Tower of London • The Northern Earls were worried they would be executed for their involvement and in a desperate attempt to avoid punishment, pushed ahead with the revolt • They raised an army of ordinary Catholics and took control of Durham cathedral • Catholic mass was celebrated across the north for 2 weeks. • They then headed south, to try and free Mary • Mary QSs was moved south to Coventry on the orders of Elizabeth, so she couldn’t escape • The rebellion failed as Spanish troops never arrived • Elizabeth’s friend (Earl of Sussex) had raised an army of 7,000 men to defend her throne. Results: • The rebellion was a serious threat to Elizabeth • She executed 450 rebels in the north • Northumberland was executed in 1572 & his head was put on a spike on the city gate • The Privy Council called for the Duke of Norfolk’s execution too, but Elizabeth released him. • Mary Queen of Scots was kept in prison for the next 14 years. • The failed plot also led the Pope to take action against Elizabeth • In 1570 he excommunicated Elizabeth from the Catholic Church • He also issued a Papal Bull (order) calling on all loyal Catholics to overthrow her hoping it would encourage another rebellion. • In 1571 Elizabeth called parliament to pass an Act making it treason to claim that she was not the rightful Queen and to bring in/print papal bulls in England. The Significance of the Revolt of the Northern Earls • It was the first and most serious rebellion by English Catholics against Elizabeth • Treason laws were made much harsher • It ended the influence of the powerful Catholic Earls in the North • It led to harsher treatment of Catholics, e.g. 1572 Elizabeth sent the Earl of Huntingdon (strict Protestant) to the north to carry out laws against Catholics (and suppress Catholicism). • Although Elizabeth’s brutal revenge on the rebels show how serious a threat it was, most Catholics in the north stayed loyal, but the Pope’s Papal Bull now put their loyalty in doubt There was little support for the revolt among the rest of the Catholic nobility and ordinary people. When faced with a choice between Elizabeth and their religion, most Catholics chose to support the Queen. 1569, was the last time English Catholics tried to remove Elizabeth by force. The future plots against her were always uncovered by Cecil & Walsingham, before they had a chance to get any public support. Despite this, the Northern Revolt & Papal Bull changed Elizabeth’s attitude towards Catholics who were now seen as potential traitors. From 1570, Elizabeth became less tolerant of recusants (people refusing to attend her church) & took increasingly tough measures against Catholics. The Ridolfi, Throckmorton & Babington plots • In the 1870s-80s, there were 3 Catholic plots to assassinate Elizabeth & replace her with Mary. • The plots were supported by France, Spain, the Pope and some Catholic nobles. • They reinforced the form Mary & from Catholics at home and abroad. Also the threat from Spain. The Ridolfi Plot (1571) • Ridolfi was an Italian banker living in England and a spy for the Pope. • He organised a plot to murder Eliz, marry Mary QS to the Duke of Norfolk & make her Queen. • The Pope & King Philip supported the plot & Philip told the Duke of Alba in the Netherlands to prepare 10,000 troops (but to only invade AFTER the English had overthrown Elizabeth). • The plot failed because Sir William Cecil intercepted coded letters & Norfolk was executed. • Mary was kept under closer watch. • Ridolfi was abroad when the plot was discovered and never returned to England. 1574: Catholic Priests and Priest Holes • From 1574 Catholic priests were smuggled into England to keep the religion alive. • They stayed with rich Catholic families, so Catholic families were kept under surveillance. • Catholic homes were raided – to find ‘priest holes’ where Catholic priests were hiding. • Catholic priests who were found could be hung, drawn and quartered (although not all were) • In 1581, Parliament also passed 2 new tougher laws against Catholics: • Recusants would be fined £20 (which would bankrupt most families) • Trying to convert people to Catholicism was now treason (punishable by death) The Throckmorton Plot (1583) • It aimed to assassinate Elizabeth and replace her with Mary. The French Duke of Guise (Mary’s cousin) would invade England with an army, funded by King Philip (Pope also supported it). • An Englishman, Throckmorton carried messages between Mary & Catholic plotters abroad. • Sir Walsingham (Secretary of State) uncovered the plot after his agents found the plans for the plot in Throckmorton’s house. Throckmorton confessed under torture and was executed. Significance: • The plots showed that Mary’s presence in England posed a serious threat • It also showed that France & Spain were a serious threat (& could invade) • Throckmorton’s papers showed a list of Catholic supporters in England, so the threat from English Catholics was also real • 1,000s of Catholics were imprisoned or kept under surveillance/house arrest • In 1585 another Act was passed to make helping Catholic priests punishable by death. • The Bond of Association was signed by the English nobles & gentry & forced them to promise to execute anyone who tried to overthrow the Queen. Weaknesses of the Plots The plots lacked public support & were uncovered by informers & spies before they had the chance to work King Philip was reluctant to destroy his alliance with Elizabeth (France was still a bigger rival) so is support for the plots was half-hearted, he rarely followed through on his promises to help the plotters or send an army The Babington Plot (1586) In 1586, Walsingham used his spy network to PROVE that Mary supported the Babington plot. His evidence persuaded Elizabeth to put Mary on trial & execute her for treason. • This was a plot to murder Elizabeth and put Mary on the throne • France would invade England with 60,000 men and Spain would also send an army • Babington was passing coded letters between Mary & her supporters in England & Europe. • But all of her letters were being intercepted and read by Walsingham. • Walsingham used his spies to follow every stage of the plot & had the letters decoded • One of Mary’s letters approved plans to murder the Queen and free Mary from prison • They also contained the names of 6 Catholics who planned to kill Elizabeth • They were arrested, hung, drawn and quartered for treason. • Mary had been implicated in plots before, but Elizabeth was always reluctant to execute her • But the proof found by Walsingham finally persuaded her to put Mary on trial • In October 1586, Mary was found guilty & was sentenced to death • But Elizabeth still hesitated, and did not sign the death warrant until February 1587. Significance 1) This plot was very significant because by 1585 England was effectively at war with Spain since Elizabeth had sent her army to help the Dutch Protestants fight the Spanish 2) This meant that Elizabeth’ situation was more dangerous than during previous plots. 3) Elizabeth’s government also became more determined to crush Catholicism 4) 1000s of recusants were arrested & 31 priests were executed 5) Mary’s execution removed the Catholic threat at home 6) English Catholics had no one to rally around, & lost hope of overthrowing Elizabeth 7) But Mary’s death increased the threat of a foreign invasion as England was at war with Spain and King Philip had been preparing an attack on England since 1585 8) Mary’s death made Philip even more determined to invade, Mary had left her claim to the English throne to King Philip upon her death Why was Mary Queen of Scots finally executed? 1 • A new Act in 1585 stated that in the event of Elizabeth’s assassination, Mary could be executed as long as she had been proved guilty & Walsingham had provided hard proof. 2 • Another reason was that by 1587, it was clear that Philip was planning to invade England • There were rumours that Spanish ships had landed in Wales & that Mary had escaped. This convinced Elizabeth that Mary had to be executed if she wanted to keep her throne. Walsingham’s Spy Network: • Walsingham (Secretary of State from 1573) had a network of spies all over England & abroad. He had spies in every English town, some were normal people paid to spy on neighbours. • He also had agents and spies in Spain, France, Germany and Italy • He hired mathematicians to crack written codes and people to open/seal letters secretly • He also pressured captured Catholic priests to spy on others for him in return for a pardon. • He used double agents to infiltrate Catholic networks - to help him discover traitors • But he only used torture against Catholic priests caught in England in the most serious cases • But 130 priests and 60 of their supporters were still executed during Elizabeth’s reign. Why did Relations with Spain get worse (1569-1588) • England had tried to stay on good terms with Spain, because Eliz wanted to avoid an expensive war that could lead to her being overthrown (English Catholics could support it) • But by the 1570s, Elizabeth wanted to have an empire of her own. • She also needed to make more money to defend her country and throne (by improving trade) • This religious, political and economic rivalry led to growing tensions between England & Spain Political and Religious Rivalry 1) Land abroad, gave countries wealth/power. By the 1580s, Eliz wanted an empire to rival Spain’s (especially as Spain had supported the Catholic plots against Eliz – even if it was half-hearted) 2) Religion was another cause of conflict. Philip opposed Elizabeth’s religious settlement 1559 3) Luckily for Elizabeth, in the 1550s Spain & France were competing to be the greatest European power and both wanted England as an ally against the other. 4) But from 1567, Spanish ships were sailing to the Netherlands with money for the Alba’s army 5) This alarmed English Protestants and Elizabeth’s Privy Council who put more and more pressure on her to send an army to help the Dutch Protestant rebels (in the Netherlands). Economic (commercial) Rivalry: The New World, privateers and Sir Francis Drake • Under Elizabeth, English merchants wanted to make big profits in the New World (Americas). • However, trading in the New World was difficult because of Spain’s power 1) Spain controlled most of the New World where there were huge profits to be made and anyone who wanted to trade there needed a licence from Spain (which it would not give): 2) But the Americas had valuable crops like tobacco, sugar, and also silver and gold 3) Elizabeth secretly encouraged privateers to trade illegally & raid Spanish ports & ships 4) At first Elizabeth denied responsibility for their actions, which delaye war with Spain Sir Francis Drake: Elizabeth sends Drake to rob Spanish colonies and ships (which infuriates Spain) 1) Spain’s support for the Ridolfi plot (1571) made her more willing to support Drake • In 1572 Eliz hired Drake to sail to the New World & steal £40,000 of Spanish silver • In 1577 she sent Drake back again with a secret mission to rob Spain’s colonies/ships • Drake brought back £400,000 of Spanish treasure & claimed an area of California in Elizabeth’s name (New Albion). He gave a lot of this money to Elizabeth • He boosted England’s finances at a time of growing concern over Spain’s threat • He became famous as the first Englishman to circumnavigate the globe. • Eliz knighted Drake as a reward, which infuriated Philip (as he saw Drake as a pirate) • Drake’s actions & his claim to California made it clear that England did not accept Spain’s domination of the New World. Elizabeth’s Support for the Dutch Rebels led to War with Spain (1585-88) • By the 1580s, tension between England & Spain had reached boiling point • At first, Eliz refused to send her army to help the Dutch rebels, because she wanted to avoid a war with Spain. So she tried to get the Spanish to leave the Netherlands in other INDIRECT ways: 1) By allowing Drake (& other English privateers) to attack and rob Spanish ships and colonies 2) By encouraging others (the French heir/mercenaries) to fight the Spanish in the Netherlands • In the 1570s, Elizabeth promised to marry the heir to the French throne (the Duke of Alencon) so that he would take an army to fight the Spanish in the Netherlands The Spanish Fury (1576) and the Pacification of Ghent (1576) • By 1576, the Spanish Govt in the Netherlands was bankrupt (the war was expensive) • After months without pay, Spain’s soldiers violently robbed Dutch towns in the “Spanish Fury” Spanish troops rebelling and robbing cities in the Netherlands in 1576. This united the Dutch Protestants & Catholics against Spain. They drew up the ‘Pacification of Ghent’ (demanding that): • Spanish troops leave the Netherlands • Spain allows the Dutch to rule themselves • The persecution of Dutch Protestants stops What did Elizabeth do? • Elizabeth sent £100,000 to help the Dutch rebels • In 1577 King Philip’s brother, Don Juan agreed to the rebels demands (but this was a trick) as just 6 months later Philip sent an even bigger army to attack the Dutch. • Elizabeth then hired a mercenary army of 6000 English & Scottish volunteers to help the Dutch. • But her plan backfired because the mercenaries destroyed Dutch Catholic churches, which caused the Catholics to make peace with Spain. • In 1578, her Privy Council urged Eliz to send her official army to help the Dutch, but she refused. The Dutch were disappointed & turned to France for help. The French Duke of Alencon arrived with an army to fight the Spanish, but by 1579 Spain had taken control again. • In 1580 Spain got even stronger after Philip won control of Portugal & its empire. • So Elizabeth gave the Duke of Alencon £70,000 to help him fight the Spanish • In 1582, Alencon took his army the Netherlands but failed to defeat Spain. • Elizabeth’s foreign policy in the Netherlands had failed & she had only managed to annoy Spain 1585: Why did Eliz finally decide to send her army to the Netherlands? (she lost her 2 main allies) • 1584 the Duke of Alencon died (so he could no longer fight the Spanish in the Netherlands) • 1 month later, William of Orange, the leader of the Dutch Protestant rebels was assassinated. • In 1585, Spain signed the Treaty of Joinville with France, agreeing to stamp out Protestantism in France/Europe meaning France & Spain were now allies against Protestantism • Elizabeth now felt she had no choice but to send her official army to the Netherlands • She signed the Treaty of Nonsuch with the Dutch rebels which promised them military help 1585: Robert Dudley’s campaign in the Netherlands was unsuccessful She sent 7,400 man army to the Netherlands led by Dudley. But he accepted the title of ‘Governor General’. Eliz was angry as it suggested that she had deposed King Philip so she told Dudley to resign this position. His army was defeated by the bigger Spanish Army as Eliz had not provided him with enough money to win. In 1587 Dudley resigned and returned to England. At the same time, Eliz had sent Drake to raid Spanish colonies in the New World to disrupt King Philip’s flow of money. Philip was furious and told the Pope he planned to invade England at the end of 1585. Drake singes the King of Spain’s beard 1587 • In 1587 Elizabeth ordered Drake to attack Spain’s most important port Cadiz • He destroyed 30 ships in 3 days – known as the ‘Singeing of the King of Spain’s Beard’ • He also stole lots of wood, meaning the Armada did not have quality barrels for food/water • Drake’s disruption delayed the Armada by a year (& meant that its food rotted in 1588). • This bought England more time to prepare for war. The Spanish Armada (1588) The Plan • By 1588, the Spanish Armada was ready to invade England • It had 130 ships with 8000 sailors & 18,000 soldiers • The Duke of Medina Sidonia would lead the Armada, but he had little experience at sea and didn’t want the job • The Armada would collect Parma’s army from France & sail to England under the protection of the Armada’s warships • Parma would march to London to depose Elizabeth & impose a Catholic government in England. 1) The Armada reached the English Channel The Armada set out in May 1588, but was delayed for a few weeks by bad weather In July the Armada was near England & signal fires were lit to warn Elizabeth English ships set sail to meet the Armada The Armada sailed up the channel in a crescent (half moon) formation, to use the large armed galleons to protect the weaker supply and army ships The English navy carried out a few minor raids, but did not inflict much damage Only 2 Spanish ships were lost (by accident) 2) The English attack the Spanish at Calais (with fire ships) and at Gravelines The Armada sailed up the English channel & anchored at Calais to wait for Parma’s army But Parma’s men didn't reach the coast in time (news had reached them too late) At midnight, the English sent 8 fireships into the Spanish ships causing panic They cut their anchors, broke formation & headed for the open sea (without Parma) The Spanish ships sailed to Gravelines, but bad weather stopped them returning to Calais The English attacked and the battle lasted many hours (5 Spanish ships were sunk) The rest were forced to sail away from France towards Scotland The English ships followed them to make sure they didn’t come back to collect Parma’s army 3) The Armada’s Journey back to Spain around Ireland was a disaster The Spanish called off the attack and returned to Spain around Scotland & Ireland Bad storms sank many ships and wrecked more on the Irish coast Many sailors died from starvation & disease – less than half the men made it back to Spain How did England defeat the Spanish Armada? !) Faster Ships • Years before the battle, England had started building smaller, faster ships (galleons) that could fire canon balls quicker & further than Spanish ships • Spanish ships were huge and slow to change direction. 2) Bad Planning & Communication (Spanish) • Philip’s plan to join with the Duke of Parma’s army in France was risky. • Parma had lots of small ships which took 48 hours to load, man and set sail. • It took too long (a week) for word to reach Parma that Medina was in the English Channel, by which time Medina had set sail to Calais. • Parma was not ready to set sail & the English were already ready to attack (leaving Medina with very little back up when anchored in France). 2) English Tactics were more effective • Spanish ships aimed to come alongside the English ones, jump on board & fight the enemy. But the English ships were faster & kept a safe distance. • They chased the Armada down the Channel, with heavy cannon fire, which forced the Spanish to arrive in France before Parma’s army was ready • As the Armada was waiting, the English sent fireships into the Spanish fleet. • This caused the Armada to panic, cut their anchors & sail away to the north • When the Spanish ships regrouped, the English attacked them in the Battle of Gravelines & the Armada was forced to sail north, chased by faster ships. 5) Bad Weather • Strong winds made it impossible for the Armada to return & pick up Parma’s army and storms wrecked or sunk Spanish ships as they tried to return home along the Scottish-Irish coasts. 2) Spanish Supplies • The Armada was not well supplied with food/weapons. Drake’s attack on Cadiz port in 1587 had destroyed food barrels. Delays in setting sail meant that by the time the English attacked the Armada it had been at sea for 10 weeks and had rotting food. 1000s died from starvation/disease. The consequences of the English victory? • Victory over the Spanish Armada gave Elizabeth a great propaganda victory • A new portrait was made, and a medal was made to commemorate her victory, it said “God blew and they were scattered”. • Elizabeth claimed that God was on the side of Protestantism • This led to a feeling of English pride and encouraged the Dutch rebels to renew their fight against the Spanish • The defeat of the Armada showed the strength of the English navy and gave England the confidence to trade and explore more widely at sea • Although Philip did not give up and continued the war for the rest of Elizabeth’s reign, the defeat had cost Spain dearly, both financially and in terms of its power • The Armada marked the start of a long decline in Spain’s power and fortunes. • English ships were sent on voyages of discovery and set up valuable new trade routes • By the end of Elizabeth’s reign, the navy was also trying to set up a new colony in Virginia • The English victory boosted Elizabeth’s popularity & strengthened the Protestant cause

Continental Drift Theory. From the discussion of the rock cycle, it has been pointed out that through Earth's external and internal processes. Earth's surface is constantly changing. However, this idea of a changing environment did not conform with the belief of earlier scientists. Rather, they thought that the geographic positions of ocean basins and continents have been static since the beginning of time. It was around the 1500s when Leonardo da Vinci, upon his discovery of fossil seashells found at the high mountains of Italy, first thought of the idea that the areas where mountains are located may have been oceans in the past. Through time, other fossils of marine organisms found far above the current sea level further supported the idea that mountains were uplifted and weathering wore them down. At around the 1800s, most scientists have accepted the idea that Earth's crust is undergoing large vertical movements or uplifting. There was also evidence of possible horizontal movements, but the scientists then were not convinced about it. Alfred Wegener showed evidence of horizontal or lateral movement of the continents in his continental drift theory. According to him, the continents have drifted around the world and have once formed a giant landmass or supercontinent called Pangaea. To support his theory, Alfred Wegener presented a set of geographical, biological, and climatic evidence.Wegener's geographical evidence included the jigsaw puzzle fit of the current continents. He pointed out that the coastlines of South America and Africa seem to fit together. He also pointed the presence of mountain ranges having similar rock types and age but separated by vast oceans, like that of the folded rocks of the Caledonian mountains. The same folded rocks run through West Africa, North America, Newfoundland, Ireland, Wales, Scotland, Greenland, and Norway, all of which are now separated by the Atlantic Ocean. A geographical evidence on the similar rock types in West Africa, North America, Greenland, and Europe is found. The biological evidence came in the discovery of similar plant and animal fossils in different continents separated by oceans. The animal fossils of Mesosaurus and Lystrosaurus indicate that they were not capable of crossing the oceans to reach the other continents. If they were, the fossils should have been more widely distributed Africa, Australia, India, and South America were too large to be carried by wind. This indicates that the areas where the fossils were found were closely linked. It has also been found out that the plant only grew in areas with subpolar climate, which would indicate that the landmasses were located near the South Pole.Lastly, for his climatic evidence, Wegener discovered that a glacial period occurred during the late Paleozoic era in Southern Africa, South America, Australia, and India. The initial explanation for this event was global cooling, but it was rejected because large tropical swamps with so much vegetation were found at the same time in the Northern Hemisphere. This further supported the idea that the supercontinent was indeed near the South Pole, and the continents in Northern Hemisphere were once near the equator. The glacial period also left glacial striations, or the scratches glaciers make as they move across on the underlying bedrock, on the aforementioned continents. For such an event to happen, the continents would have to be connected. SCIENCE PIONEER. Alfred Wegener (1880-1930). Alfred Wegener was a German polar researcher, geophysicist, and meteorologist. He was known for his work on the continental drift theory. In his effort to defend his work, he went to the Greenland ice sheet where he died.Even with all the compelling evidence, the continental drift theory hardly convinced the scientific community at that time because Wegener was unable to identify a credible mechanism that drives the continental drift. He was unable to clearly explain how the continents moved and how the larger continents broke through the ocean floor. Eventually, critics of the continental drift began to accept the theory when new evidence supporting the theory was discovered. The new evidence led to a more encompassing theory the theory of plate tectonics. This theory provided a more convincing explanation as to how the continents moved. The evidence that paved the way for the theory of plate tectonics was the idea of wandering poles. Scientists began studying volcanic rocks to determine the location of the magnetic poles. When volcanic rocks crystallize, the minerals with magnetic properties align themselves parallel to Earth's magnetic field at the time the minerals were formed. This finding allowed scientists to determine the polarity of Earth's magnetic field and the magnetic inclination that showed the location of the poles. Upon studying the paleomagnetism of the rocks, geophysicists found out that rocks from various locations point to different magnetic north poles, suggesting that the poles have wandered. Since movement of magnetic poles is very unlikely, scientists have accepted the idea that the continents are indeed moving. And if the continents are moving, scientists thought that maybe the ocean basins are moving too. They also discovered that some rocks showed magnetic reversals, which led them to believe that the magnetic north pole now was not always the magnetic north pole. Seafloor Spreading. After World War II, exploration on the ocean floor became the focus of many geologic studies. It was only then that the ocean ridge system was discovered. A geologist in Princeton University named Harry Hess, along with other scientists, studied this ocean ridge system and hypothesized that the oceanic crust was moving away from the ridge. His hypothesis, known as seafloor spreading, showed that the ocean floor is split along the ridge where the magma rises to form the new ocean floor.Because of this, rocks located near the ridge are younger than those that are located magnetic polarity of Earth is also preserved in those rocks. Withe ridge scientists were able to see the magnetic reversals in the ocean floor, and they were able to make use of information to determine that the ocean floor is moving at a rate of about 10 cm per year. Plate Tectonics. Confirmation of the seafloor spreading hypothesis proved that continents are not moving above the ocean floor. Rather, it is the fragments of the lithosphere. The lithosphere is the rigid layer that is composed of the uppermost mantle and the crust that carry the continents and the ocean basins along. These fragments of the lithosphere are called plates. Underneath the lithosphere is a weaker region in the mantle known as asthenosphere that behaves like a fluid. Thus, the lithosphere floats above the asthenosphere, making it detached and free to move. This became the basis of the theory of plate tectonics. Now that it has been made clear that it is the plates which are moving, the question as to how they move remained. Sir Arthur Holmes proposed the driving force for this plate movement in 1919. He suggested that the movement in the mantle carries the plates along. It was previously discussed that Earth's interior is very hot due to the heat produced by radioactive decay. Convection takes place in the mantle, keeping the asthenosphere hot and weak. The convection currents produced in the asthenosphere are the ones carrying the lithospheric plates and making them move. However, convection currents are not enough. Mechanisms such as ridge push and slab pull aid the convection currents to slowly move the lithospheric plates. Ridge push occurs at mid ocean ridges which are higher in elevation than the surrounding trenches and abyssal plains. The new ocean floor from the ridge is hot and relatively thin. As it moves away from the ridge, it cools down and gets denser, heavier, and thicker. Below this cooling ocean floor is the asthenosphere, which is less dense. This area becomes a massive shear zone and the new ocean floor will effectively slide down the slope of the asthenosphere. When the plate collides with another plate with lesser density, the denser plate sinks and a subduction zone is formed. When the subducting plate sinks, it pulls on the rest of the plate behind it. These mechanisms explain the movement of the plates.Earth has seven major lithospheric plates that account for 94% of Earth's surface. These are the North American Plate, South American Plate, Pacific Plate, African Plate, Eurasian Plate, Indo-Australian Plate, and Antarctic Plate. These plates are constantly moving relative to the other plates. Thus, the interaction of plates occurs mostly along the boundaries. These movements are plotted using information from earthquakes and volcanic activities. There are three main types of plate boundaries: convergent, divergent, and transform boundaries Convergent boundaries are boundaries where two plates move towards each other A convergent boundary is also known as destructive margin since this is where the collision between two plates occhins. There are three types of convergence-oceanic oceanic, oceanic-continental, and continental-continental. Trenches are features of the ocean floor that are present in both oceanic-oceanic boundary and oceanic-continental boundary. Subduction occurs at the trenches, therefore, these are characterized as the deepest parts of Earth. A divergent boundary is the opposite of convergent boundary: two plates move away from each other. Divergent boundaries create new crust; thus, they are also known as constructive margins. The ocean ridge system is a divergent boundary where new ocean floor is produced as magma rises, pushing the older rocks aside.Transform boundary is also known as conservative plate margin since two plates just move past one another, neither creating nor destroying land. Earthquake epicenters are usually detected at transform boundaries because the rocks tend to break and not fold or sink, like in convergent boundaries. Evolution of the Ocean Basins. Both the movement of the plates and seafloor are responsible for the evolution of ocean basins. Along the divergent boundary where ocean ridge systems are found, magma is released and new ocean floor is created. Along convergent boundaries, the ocean floor is being destroyed. The evolution of the ocean basins started during the time when Pangaea was still present and was surrounded by the vast ocean or superocean known as Panthalassa, also called Paleo-Pacific or "old Pacific." Upon the initial break up of Pangaea into Laurasia and Gondwanaland, the Tethys Sea began to form. Then, the Eurasian and North about, forming the North Atlantic. The South Atlantic only started to form when the African Plate and South American Plate separated. The continued movement of the plates created the Himalayas at one side and separated the Pacific Ocean and Atlantic Ocean at the other side, which consequently formed the current ocean basins. Both the movement of the plates and seafloor are responsible for the evolution of ocean basins. Along the divergent boundary where ocean ridge systems are found, magma is released and new ocean floor is created. Along convergent boundaries, the ocean floor is being destroyed. The evolution of the ocean basins started during the time when Pangaea was still present and was surrounded by the vast ocean or superocean known as Panthalassa, also called Paleo-Pacific or "old Pacific." Upon the initial break up of Pangaea into Laurasia and Gondwanaland, the Tethys Sea began to form. Then, the Eurasian and North about, forming the North Atlantic. The South Atlantic only started to form when the African Plate and South American Plate separated. The continued movement of the plates created the Himalayas at one side and separated the Pacific Ocean and Atlantic Ocean at the other side, which consequently formed the current ocean basins.Continents do not immediately end at the point where the ocean meets the land. They may extend slightly into the oceans. The portion of the continent that is submerged is called continental margin. There are two types of continental margin: passive margin and active margin. A passive continental margin consists of a continental shelf, continental slope, and continental rise. It is not associated with plate boundaries; thus, there are very little tectonic activities. An active continental margin only has a continental shelf and a continental slope. It is associated with plate boundaries; thus, a main feature of this boundary is a trench. The different features of a continental margin are the following: 1. The continental shelf is the gently-sloping submerged portion of the continent. 2. The continental slope is the steep slope after the continental shelf. It is still part of the continent. 3. The continental rise is the gently-sloping area after the continental slope and before the ocean floor. 4. The trenches are the deepest parts of the ocean. These are narrow depressions caused by the subduction of the ocean floor along the convergent boundaries. 5. The mid-oceanic ridge is the mountain range system in the ocean. It is responsible for the production of new ocean floor. This is the region where new magma constantly emerges from. SCIENCE CAREER. A scientific illustrator uses art to inform and communicate complex details and concepts of science. He/She makes use of scientifically informed observations and research along with his/her technical art and aesthetic skills to make accurate representations. In Natural History, the scientific illustrators recreate how the extinct species look like by working with scientists and fossil records. Moreover, with the advances in technology, illustrators are now into 3D modelling, animation, and video making. Earth's History. All the processes that have been discussed require long periods of time to create a noticeable change on Earth's surface. You can just imagine how long it would take to create an oceanas vast as the Pacific Ocean if the ocean floor moves only at about 10 cm/year. It is then important to know the history of Earth to learn the complexities of its past and be able to use it to understand the present. Just like learning the history of a country that requires one to read a lot of books, learning the history of Earth involves studying a lot of rocks. Rocks, especially sedimentary rocks, contain a lot of information about Earth's past. It holds the key to most of the geologic processes that happened on Earth and the key to uncovering how life on Earth evolved. But these discoveries are worthless if there is no time perspective. Thus, one of the most important contributions of geologists to mankind is the geologic time scale, which holds a history that is exceedingly long.

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