What is a main difference between currents and tides?

Currents are like rivers of water in the ocean and tides are the regular rise and fall of water each day.

Tides are the direction water travels and currents are the speed of travel.

Tides are caused by the currents’ constant movement.

Currents are always caused by the tides that fall.

Inlets are the water-filled spaces between barrier islands. As tides change, the amount of water in an inlet may change. Changes to the shape of an inlet opening may be caused by _________________.

A. children building sandcastles on the beach

Ocean Shore Zone | Quizalize

Earthquakes are generated when a fault on the edges of the plates occurs. That is, part of the edges of the plate breaks. The breaking causes shaking on the plates that are felt on the surface. This shaking is what we call earthquakes. When part of the plate breaks during the collision, shifting of the ocean floor happens. During the shifting, energy is released. This energy pushes the ocean water above. When this ocean water reaches the shores, we call them tsunami. During subduction, as plates reach the mantle, it will eventually be melted as magma. When these magmas find a weak spot in the crust, it forms a volcano. This volcano erupts when the crust cannot withstand the pressure exerted by the magma. Earthquakes, tsunami and eruption of volcanoes are natural disasters brought by the activity of the subduction zone. These natural disasters may cause the loss of lives, damage to properties, displacement to other areas, and livelihood.

Soils Southeast Asia, on balance, has a higher proportion of relatively fertile soils than most tropical regions, and soil erosion is less severe than elsewhere. Much of the region, however, is covered by tropical soils that generally are quite poor in nutrients. Often the profusion of plant life is more related to heat and moisture than to soil quality, even though these climatic conditions intensify both chemical weathering and the rate of bacterial action that usually improve soil fertility. Once the vegetation cover is removed, the supply of humus quickly disappears. In addition, the often heavy rainfall leaches the soils of their soluble nutrients, hastens erosion, and damages the soil texture. The leaching process in part results in laterites of reddish clay that contain hydroxides of iron and alumina. Laterite soils are common in parts of Myanmar, Thailand, and Vietnam and also occur in the islands of the Sunda Shelf, notably Borneo. The most fertile soils occur in regions of volcanic activity, where the ejecta is chemically alkaline or neutral. Such soils are found in parts of Sumatra and much of Java in Indonesia. The alluvial soils of the river valleys also are highly fertile and are intensively cultivated. Climate All of Southeast Asia falls within the warm, humid tropics, and its climate generally can be characterized as monsoonal (i.e., marked by wet and dry periods). Changing seasons are more associated with rainfall than with temperature variations. There is, however, a high degree of climatic complexity within the region. Temperatures Regional temperatures at or near sea level remain fairly constant throughout the year, although monthly averages tend to vary more with increasing latitude. Thus, with the exception of northern Vietnam, annual average temperatures are close to 80 °F (27 °C). Increasing elevation acts to decrease average temperatures, and such locations as the Cameron Highlands in peninsular Malaysia and Baguio in the Philippines have become popular tourist destinations in part because of their relatively cooler climates. Proximity to the sea also tends to moderate temperatures. Precipitation Much of Southeast Asia receives more than 60 inches (1,500 millimeters) of rainfall annually, and many areas commonly receive double and even triple that amount. The rainfall pattern is distinctly affected by two prevailing air currents: the northeast (or dry) monsoon and the southwest (or wet) monsoon. The northeast monsoon occurs roughly from November to March and brings relatively dry, cool air and little precipitation to the mainland. As the southwestward-flowing air passes over the warmer sea, it gradually warms and gathers moisture. Precipitation is especially heavy where the airstream is forced to rise over mountains or encounters a landmass. The east coast of peninsular Malaysia, the Philippines, and parts of eastern Indonesia receive the heaviest rains during this period. The southwest monsoon prevails from May to September, when the air current reverses and the dominant flow is to the northeast. The mainland receives the bulk of its rainfall during this period. Over much of the southern Malay Peninsula and insular Southeast Asia there is little or no prolonged dry season. This is especially marked in much of the equatorial region and along the east coast of the Philippines. While the dry and wet monsoons are important in explaining rainfall patterns, so too are such factors as relief, land and sea breezes, convectional overturning and cyclonic disturbances. These factors often are combined with monsoonal effects to produce highly variable rainfall patterns over relatively short distances. While many of the cyclonic disturbances produce only moderate rainfall, others mature into tropical storms—called cyclones in the Indian Ocean and typhoons in the Pacific—that bring heavy rains and destruction to the areas over which they pass. The Philippines are particularly affected by these storms. Plant life Tropical forests in Southeast Asia Tropical forests in Southeast Asia The seasonal nature and pattern of Southeast Asia’s rainfall, as well as the region’s physiography, have strongly affected the development of natural vegetation. The hot, humid climate and enormous variety of habitats have given rise to an abundance and diversity of vegetative forms unlike that in any other area of the world. Much of the natural vegetation has been modified by human action, although large areas of relatively untouched land still can be found. The vegetation can be grouped into two broad categories: the tropical-evergreen forests of the equatorial lowlands and the open type of tropical-deciduous, or “monsoon,” forests in areas of seasonal drought. The evergreen forests are characterized by multiple stories of vegetation, consisting of a variety of trees and plants. Although a large diversity of tree species is found in these forests, members of the Dipterocarpaceae family account for roughly half of the varieties. Deciduous forests are found in eastern Indonesia and those parts of the mainland where annual rainfall does not exceed 80 inches. Just as in the equatorial forest, a wide variety of species is normally the rule. Certain species, such as teak, have become highly valued commercially. Teak is found in parts of Indonesia, Myanmar, Thailand, and Laos. In addition to these two basic types of vegetation, other regional patterns reflect topography. Especially noteworthy are coastal and highland plant communities. Mangrove belts, of which there are more than 30 varieties, occur where silt is deposited in coastal areas. Upland forests dominated by maples, oaks, and magnolias are found especially on mainland mountain slopes. Human activity has been rapidly altering the stands of virgin forest in Southeast Asia. Most deforestation results from removal for fuelwood and clearing for agriculture and grazing. Although only a relatively small portion of the total land area has been permanently cleared for cultivation—e.g., in Java (Indonesia) and western Luzon (the Philippines)—in some areas shifting cultivation has brought about the replacement of virgin forest with secondary growth. In addition, nearly all countries have commercial logging industries; notable are those in Indonesia, Malaysia, Thailand, and Myanmar. A growing problem has been illegal logging. Thus, timber harvesting has come to contribute significantly to deforestation. Programs in social forestry and reforestation have yet to halt the rapid denuding of the landscape. Animal life Southeast Asia is situated where two major divisions of the world’s fauna meet. The region itself constitutes the eastern half of what is called the Oriental, or Indian, zoogeographic region (part of the much larger realm of Megagaea). Bordering along the south and east is the Australian zoogeographic region, and the eastern portion of insular Southeast Asia—Celebes (Sulawesi), the Moluccas, and the Lesser Sunda Islands—constitutes a transition zone between these two faunal regions. a classroom in Brazil More From Britannica education: Southeast Asia Southeast Asia is notable, therefore, for a considerable diversity of wildlife throughout the region. These differences are especially striking between the species of the eastern and western fringes as well as between those of the archipelagic south and the mainland north. The differences stem largely from the isolation, over varying lengths of geologic time, of species following their migration from the Asian continent. In addition, the tropical rain forests in many parts of the region, with their great diversity of vegetation, have made possible the development of complex communities of animals that fill specialized ecological niches. Especially numerous are arboreal and flying creatures. orangutans orangutansOrangutans (Pongo pygmaeus) in Sumatra, Indonesia. The distinction between the two faunal regions is best depicted by their mammal populations. In general, Australia is inhabited largely by marsupials (pouched mammals) and monotremes (egg-laying mammals), while Southeast Asia contains placental mammals and such hybrid species as the bandicoot of eastern Indonesia. Small mammals such as monkeys and shrews are the most numerous, while in many areas the larger mammals have been pushed into more remote areas and national preserves. Bears, gibbons, elephants, deer, civets, and pigs are found in both mainland and insular Southeast Asia, as are diminishing numbers of tigers. The Malayan tapir, a relative of the rhinoceros, is native to the Malay Peninsula and Sumatra, while the tarsier is found in the Philippines and parts of Indonesia. A number of rare endemic species are found in Indonesia and East (insular) Malaysia, including the Sumatran and Javan rhinoceros, the orangutan, the anoa (a dwarf buffalo), the babirusa (a wild swine), and the palm civet. As the pace of development accelerates and populations continue to expand in Southeast Asia, concern has increased regarding the impact of human activity on the region’s environment. A significant portion of Southeast Asia, however, has not changed greatly and remains an unaltered home to wildlife. The nations of the region, with only few exceptions, have become aware of the need to maintain forest cover not only to prevent soil erosion but to preserve the diversity of flora and fauna. Indonesia, for example, has created an extensive system of national parks and preserves for this purpose. Even so, such species as the Javan rhinoceros face extinction, with only a handful of the animals remaining in western Java

Into the Sea What Is Erosion? Have you ever made a sand castle at the beach? You must pick a good spot for it. If it is too close to the water, waves will quickly wash it away. Ocean waves and wind can also wash away land. They can change the shape of an island, which is land circled by water. When wind and water change the shape of Earth, it is called erosion. Waves are the biggest cause of erosion at the beach. Ocean waves are always active and moving onto the shore. They carry the sand away bit by bit. Strong waves are one of the properties of big storms. These waves explode as they crash onto the beach. Storm waves can move a lot of sand quickly. Erosion of Beaches. Some people build houses near the ocean. Waves take away the sand between the houses and the sea. As the beach disappears, the water gets closer to houses and other solid buildings on the beach. Some buildings can even be washed away. Erosion of Rocks. Erosion also happens on steep, rocky cliffs or sharp slopes. First, waves smash into the bottom of the cliffs. Then they carry away tiny pieces of rock. Over time, many small pieces of rock wash away from the bottom of the cliff. This makes the top of the cliff weak.The cliff can crumble and fall into the sea. Stopping Erosion. Some local communities work to stop erosion to nearby beaches. These towns have built sea walls of large boulders or rocks. The rocks are placed in a row in the sea. When waves hit the sea wall, they slow down. Then the waves can't pull sand away.Some towns make rules about buildings on the beach. New buildings must be far from the water. Then they won't wash away like a sand castle.

Write questions based on the text: How long could you survive at sea? One day? Two? And when would you start to lose hope? When Robert Hewitt came to the surface, he realized straight away that something was wrong. He’d been diving for sea urchins and crayfish off the coast of New Zealand with a friend, and had decided to make the 200-metre swim back to shore alone. But instead, strong underwater currents had taken him more than half a kilometre out to sea. Lying on his back in the middle of the ocean, Robert told himself not to panic. He was a strong swimmer and he was wearing his thick wetsuit. 'I'm not going to die. Someone will come,' he told himself. But three hours passed and still no one had come for him. Robert would soon have to make a tough decision. He was now a long way from the coast and the tide was taking him further out, but he decided not to try to swim for shore. He felt it was better to save his energy and hold on to his brightly coloured equipment. But the decision was not an easy one. 'l just closed my eyes and said, "You've made the right decision. You've made the right decision" until that's all I heard,' he remembers. As night approached, Robert established a pattern to help him survive in the water. To stay warm, he kept himself moving and took short naps of less than a minute at a time. Every few hours, he called out to his loved ones: 'Just yelling out their names would pick me up and then I would keep going for the next hour and the next hour and the next.' When he woke the next morning, he couldn't believe he was still alive. Using his bright equipment, he tried to signal to planes that flew overhead. But as each plane turned away, his spirits dropped. He managed to drink water from his oxygen tank to keep himself alive, but as day turned to night again he started to imagine things. Robert woke on the third day to a beautiful blue sky. Now seven kilometres off the coast, Robert decided he had to swim for it. But the sun was so strong and Robert quickly ran out of strength. Hope turned to disappointment yet again: 'l felt disappointed in myself. I thought I was a lot fitter. I thought I would be able to do it.' Robert then started to think he might not survive. On the fourth day, the lack of food and water was really starting to affect him. Half unconscious, and with strange visions going through his head, he thought he saw a boat coming towards him with two of his friends in. Another vision, surely. But no - 'They put me in the boat and I said something like "Oh, how's it going, what are you guys doing here?"' Then he asked them the question that he'd asked in all his visions: 'Can I have some water?' As they handed him the water and he felt it touch his lips, he knew. This was not a vision. He'd been found! After four days and three nights alone at sea, Robert had been found! Sunburnt, hungry and exhausted, but alive.

Ocean Animals Many kinds of animals live in the ocean. They are part of the ocean community. Let's meet some of these ocean animals. Most of the ones in this book are mammals, fish, or reptiles. I am a dolphin. I have a sleek body and a strong tail to swim fast. I live in a group called a pod, and I like to eat fish. I whistle to talk to other dolphins. I am a walrus, and I have ivory tusks. I use them to dig for clams and to protect myself. I live on ice and in cold water. My thick layer of fat keeps me warm. I am a hammerhead shark, and my head has a very funny shape. My eyes and nostrils are at the ends of lobes. I like to eat fish. I am a California sea lion. I am smart, noisy, and playful. I bark like a dog, and I am covered by short fur. I eat squid, octopus, and fish. I am an octopus. I have a soft body and no skeleton. I have eight arms with suckers. I shoot black ink from my body to hide and escape from danger. I can also change the color of my skin. I am a great white shark. I am a large and fierce shark. I have very sharp teeth that are shaped like triangles. I eat seals, dolphins, and fish. I am a manta ray. I have fins that look like wings. I am related to stingrays, but I do not sting. I am a sea horse, but I am not a horse. I am a fish. I change color to hide. Shrimp are my favorite food. Male sea horses, not females, carry eggs until they hatch. I am a leatherback turtle, the biggest turtle in the world. I lay eggs on land. Jellyfish are my favorite food. I am covered with leathery skin instead of a shell. I am a blue whale. I am the largest mammal ever to live. I make deep sounds that move through water. I eat tiny animals called krill. The ocean is home to all these animals. Many of them are endangered. They all suffer because of pollution and hunting. Keeping our oceans clean will help keep these animals alive.

The collision of oceanic and continental crust as well as the collision of two oceanic crust results in the formation of trenches and volcanic arcs. This will also result in the generation of earthquakes, tsunamis and volcanic eruptions. Earthquakes are generated when a fault on the edges of the plates occurs. That is, part of the edges of the plate breaks. The breaking causes shaking on the plates that are felt on the surface. This shaking is what we call earthquakes. When part of the plate breaks during the collision, shifting of the ocean floor happens. During the shifting, energy is released. This energy pushes the ocean water above. When this ocean water reaches the shores, we call them tsunami. During subduction, as plates reach the mantle, it will eventually be melted as magma. When these magmas find a weak spot in the crust, it forms a volcano. This volcano erupts when the crust cannot withstand the pressure exerted by the magma.

Camera traps Technology is being used more and more in film and photography, For example, wildlife photographers sometimes use camera traps. When a photographer uses a camera frap the camera is hidden; for example, in a tree or on the ground so the animals cannot see it. When an animal moves near the camera, the camera is furned on and it takes a photo or a short film. Sometimes the camera is fixed onto an animal so it can take a film as the animal moves. The film then helps us to leam much more about the animal's life. Photo engineers of National Geographic design camera traps to help photographers hide cameras, for example in birds nests or on the ocean floor. They've designed camera traps for National Geographic photographers like Steve Winter, who takes photos of wild animals such as tigers, leopards, jaguars and bears. The camera trops are set up so that the animal looks straight into the camera. Steve thinks that if people see good photos of wild animals, they'll understand more about the animals and want to protect them. Photo engineers have to design cameras that will not break when they're being used in places like jungles or the ocean. Sometimes photographers use small remote-controlled cars to carry cameras. Technology is improving all of the time and helping photographers to take amazing photos. Thanks to the technology of camera traps, we can all see the world in new and interesting ways.

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 oceanS as 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.The geologic time scale divides the history of Earth into different blocks of time by using relative dating. Since geologists use rocks to understand Earth's history, dating does not give accurate numerical dates, it only tells that an event preceded the relative dating places these rocks in their proper sequence of formation. But relative other. This method is still widely used today, alongside a more accurate method called absolute dating, which uses radioactive elements. With relative and absolute dating. geologists can trace the history of Earth. Relative Dating. Relative dating requires one to know the basic principles such as law of super-position, principle of original horizontality, principle of cross-cutting relationships, and unconformities.Law of Superposition The law of superposition is the most basic principle in relative dating. It states that in an undeformed sequence of sedimentary rock, the layers found at the top are the youngest rocks and the layers at the bottom are the oldest. It may seem too obvious, but this principle has only been clearly stated in 1669 by the Danish anatomist, geologist, and priest, Nicolaus Steno. Principle of Original Horizontality Along with the law of superposition, Steno stated that an undeformed sequence is the one where the layers are still in a horizontal position. This follows the principle of original horizontality, which states that sediments are deposited horizontally. Principle of Cross-Cutting Relationships The principle of cross-cutting relationships determines which events occurred first depending on which rocks are affected. The geologic layer that cuts another is younger than the layer it cuts across.Unconformities Rock layers that have not been interrupted are considered conformable. These sites represent spans of geologic time. But there is no place on Earth that has a complete conformable stratum since external and internal processes have always interrupted the deposition of the sediments. These breaks in the record of the rock strata are called unconformities. Using unconformities, geologic events are determined. There are three basic types of unconformities angular unconformity, disconformity, and nonconformity. Angular unconformity is characterized by having tilted or folded sedimentary rocks below younger, horizontal layers of rock. Disconformity is determined where there are missing parallel rock layers. Erosion takes place and removes the younger top layers and then deposition would once again happen. Nonconformity is characterized by an igneous or metamorphic rock found below a sedimentary rock. Figure 3-13. Three basic types of unconformities Using these principles for relative dating, one can determine the order of events However, relative dating does not give a time element as to when they happened. Absolute Dating For a much more accurate method of determining the history of Earth, geologists make use of absolute dating. This method uses unstable elements to determine the exact age of rocks. Isotopes are elements that have the same number of protons but different number of neutrons. Most isotopes are stable but some may be unstable. This is because the forces that bind the protons and neutrons in the nucleus of the isotope are not strong enough to hold them together, resulting in a radioactive decay, The unstable isotopes are called radioactive isotopes or parent isotopes. When these parent isotopes undergo radioactive decay, new isotopes, known as daughter products, are formed. The time it takes for one-half of the nuclei in the sample to decay is called half-life. This amount of time is fixed for each kind of radioactive isotope no matter what physical conditions it is subjected to. The ratio of parent daughter isotope determines how many half-lives have passed. If it is 1:1, then one half-life has passed; if it is 1:3, then two half-lives have passed; and if 1:7, then three half-lives have passed, and so on. Therefore, using the concept of half-life and parent-daughter ratio, geologists can determine the exact age of the sample. This method is called radiometric dating. It uses five radioactive isotopes to determine the age of rocks. For dating rocks that are about a million years old, rubidium-87, thorium-232, and the two isotopes of uranium (U-238 and U-235) are used. The fifth radioactive isotope is potassium-40, which has a half-life of 1.3 billion years. With these radioactive elements, determining the accurate age of rocks becomes easier. For dating events that are more recent, radiocarbon dating is used. This method uses carbon-14. Carbon-14 has a half-life of 5730 years and can be used to date back events up to 75000 years. All organisms contain a small amount of carbon-14, which is proportional with the amount of carbon-12. When an organism dies, the carbon-14 decays and is no longer replaced. The amount of carbon-14 left in the sample is then compared to the amounts of carbon-12 present, and radiocarbon dates can then be determined. This method has been particularly useful for anthropologists, archeologists, historians, and geologists for events that are much more recent.Fossils Aside from rocks, geologists also use the remains of living organisms in understanding Earth's history. Some fossils are formed from parts of an organism (body fossil), while some provide signs or clues as to which life-forms were present at that time (Frace fossils). Fossils contain a lot of information about the past the kind of organisms that have lived, the environment where organisms lived, and the evolution organisms underwent as their environment changed. However, not all organisms turned into fossils, therefore, scientists cannot learn everything about the past using fossils alone. There are also fossils that are used to determine the age of a rock. These are index fossils and these are only found in rocks of a particular age. The organisms that turned into index fossils have a relatively short life-spanning from a few million years to a few hundred million years. Index fossils are also found in most of the common rocks around the world, which makes them easier to identify.The methods used for dating the age of rocks are also used for fossils. Absolute dating is more commonly used since it can give exact numerical dates for the age, but relative dating can also be used to determine which fossils are older.

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