Earth Structure By Cathy Pons

When rocks experience a force that exceeds their strength, they fracture and create vibrations known as earthquakes. These vibrations travel through the Earth's crust, causing the ground to shake. Earthquakes can occur due to various factors such as tectonic plate movements, volcanic activity, or human-induced activities like mining or underground explosions. The answer "earthquakes" accurately describes the phenomenon resulting from the breaking of rocks under significant force.

The word "metamorphic" is derived from the Greek word "metamorphoun," which means "to change form." Therefore, the correct answer is "change."

The part of the earth colored yellow is the inner core. The inner core is the solid, dense center of the earth that is primarily composed of iron and nickel. It is located beneath the outer core and is responsible for generating the earth's magnetic field. The inner core is thought to be yellow in color due to the extreme pressure and temperature conditions present in this region of the earth.

Most earthquakes happen along plate boundaries. This is because plate boundaries are areas where tectonic plates interact and collide with each other. The movement and collision of these plates create stress and pressure, which can lead to the release of energy in the form of an earthquake. Therefore, it is along these plate boundaries that most earthquakes occur. The other options, such as at night or in the inner core, are not accurate explanations for the occurrence of earthquakes.

The inner core is the hottest, most dense part of the Earth. It is a solid sphere made mainly of iron and nickel, with temperatures reaching up to 6,000 degrees Celsius. The immense pressure at the center of the Earth causes the inner core to remain solid despite its extremely high temperature. The outer core, on the other hand, is also molten but less dense than the inner core. The mantle, located between the outer core and the Earth's crust, is semi-solid and less dense than both the inner and outer core.

The movement of the outer core generates a magnetic field, which is responsible for Earth's magnetism. This magnetic field protects the planet from harmful solar radiation and plays a crucial role in various natural processes, such as the orientation of compass needles and the formation of auroras. Therefore, the correct answer is magnetism.

Scientists discovered changes in the earth's interior by studying seismic waves. Seismic waves are vibrations that travel through the earth's layers during an earthquake or other seismic events. By analyzing the behavior and characteristics of these waves, scientists can infer information about the composition, structure, and dynamics of the earth's interior. This includes identifying the boundaries between different layers, studying the movement of tectonic plates, and detecting the presence of seismic activity such as volcanic eruptions or earthquakes. Therefore, seismic waves provide valuable insights into the earth's interior without the need to physically travel to the core.

Shearing is the force that causes plates to move sideways past each other. When two tectonic plates slide horizontally in opposite directions, they experience shearing forces. This type of movement often occurs along transform boundaries, such as the San Andreas Fault in California. Shearing forces cause rocks to deform and fracture, leading to earthquakes. Tension and compression forces, on the other hand, cause plates to move away from or towards each other, respectively, but not sideways.

The plates of the crust float on the asthenosphere inside the earth. The asthenosphere is a semi-fluid layer of the mantle that lies beneath the lithosphere. It is characterized by its ability to flow and deform over long periods of time due to its high temperature and pressure. This allows the crustal plates to move and interact with each other, causing phenomena such as earthquakes, volcanic activity, and the formation of mountain ranges. The asthenosphere acts as a lubricating layer that enables the movement of the crustal plates.

Compression is the force that squeezes rocks or plates together. When two objects are pushed towards each other, compression occurs. This force causes the rocks or plates to be pressed tightly against each other, resulting in a decrease in their volume. This can lead to the formation of mountains, as the Earth's tectonic plates collide and compress against each other, causing the rocks to fold and buckle. Compression is also responsible for the formation of faults and earthquakes when the stress becomes too great for the rocks to handle.

The crust and upper mantle make up the lithosphere. The lithosphere is the rigid outer layer of the Earth, consisting of the crust and a portion of the upper mantle. It is divided into several tectonic plates that float on the semi-fluid asthenosphere beneath it. The lithosphere is responsible for the formation of continents, ocean basins, and the movement of tectonic plates. It is also where most geological activity, such as earthquakes and volcanic eruptions, occurs.

Alfred Wegener is the correct answer because he was the scientist who first proposed the theory of continental drift in the early 20th century. He suggested that all the continents were once joined together in a supercontinent called Pangaea, and over time, they gradually drifted apart to form the current configuration of continents. Wegener's theory revolutionized the understanding of Earth's geological history and laid the foundation for the modern theory of plate tectonics.

Igneous rocks are formed when magma or lava cools and hardens. Magma is molten rock located beneath the Earth's surface, while lava is magma that reaches the surface through volcanic eruptions. As the magma or lava cools, it solidifies and forms igneous rocks. Sedimentary rocks are formed through the accumulation and compaction of sediments, while metamorphic rocks are formed through the transformation of existing rocks under high heat and pressure. Therefore, the correct answer is igneous.

Tension is the force that pulls rocks apart. When rocks are subjected to tension, they experience a pulling force that causes them to stretch and ultimately break apart. This force is commonly observed in areas where tectonic plates are moving away from each other, such as in divergent boundaries or rift zones. Tension can also occur in other geological processes, such as the stretching and thinning of rocks in fault zones.

The rock cycle is a continuous process that involves the transformation of rocks from one type to another over millions of years. It showcases how rocks are constantly changing and evolving, rather than remaining stagnant. Therefore, the correct answer "on a continuing journey" accurately describes the concept of the rock cycle.

The given answer states that none of the above answers are correct. This means that none of the options listed in the question accurately describe an occurrence in the rock cycle. The rock cycle involves the continuous transformation of rocks between the three main types: sedimentary, igneous, and metamorphic. Therefore, the correct answer is that none of the listed options occur in the rock cycle.

The given statement is incorrect. The earth is actually estimated to be around 4.5 billion years old, not million years old. This estimation is based on various scientific methods and evidence such as radiometric dating of rocks and minerals.