Earth's Changing Surface! Trivia Quiz

The most common cause of earthquakes is the movements of the Earth's crust. Earthquakes occur when there is a sudden release of energy in the Earth's crust, which causes the ground to shake. This energy release is typically caused by the movement of tectonic plates, which are large sections of the Earth's crust that float on the semi-fluid mantle beneath them. As these plates interact with each other, they can either collide, slide past each other, or move apart, resulting in earthquakes. These movements can cause the rocks to break and slip along fault lines, leading to seismic activity.

Plant roots have the ability to grow into cracks in rocks. As the roots grow, they exert pressure on the rocks, forcing them apart. This process is known as root wedging. Over time, as the roots continue to grow and exert pressure, the cracks in the rocks widen, eventually causing the rocks to break into smaller pieces. This is a natural process that helps in the weathering and erosion of rocks by plants.

Dunes are hills of sand that are formed by wind erosion in the desert. The wind blows sand particles and deposits them in certain areas, creating these distinctive hills. Dunes are a common feature in desert landscapes and can vary in size and shape. They are often formed by the interaction of wind direction, sand availability, and other environmental factors.

A fast-flowing river can gradually cut through layers of rock, creating a canyon. Over time, the force of the water erodes the rock, carving out a deep and narrow valley with steep sides. The continuous flow of the river wears away at the rock, widening and deepening the canyon over thousands or even millions of years. Canyons are commonly found in areas with high erosion rates, such as arid regions or areas with steep gradients.

A delta is formed by water erosion. Deltas are landforms that are created at the mouth of a river where it meets a body of water, such as an ocean or a lake. Over time, the river carries sediment, such as sand, silt, and clay, downstream. When the river reaches the body of water, the water slows down and loses its energy, causing the sediment to settle and accumulate. This process, known as deposition, creates a fan-shaped landform called a delta.

Plate tectonics has shifted the location of the region over time. This explanation suggests that the movement of tectonic plates has caused the ancient deserts to be located in places that now experience temperate climates. As the plates shift, the landforms and climates change, leading to the transformation of deserts into temperate regions. This process is a natural occurrence and has occurred over a long period of time.

Above-average rainfall and flash flooding are not causes of desertification. Desertification refers to the process of land degradation in which fertile land becomes desert-like, typically due to human activities such as deforestation and overcultivation. While above-average rainfall and flash flooding can have negative impacts on ecosystems, they do not directly contribute to the conversion of fertile land into desert. In fact, excessive rainfall can actually be beneficial for preventing desertification by providing water for vegetation growth.

The correct answer is coarse grains of sand. When wind blows, it is able to pick up and transport particles that are smaller and lighter. However, only sand-sized particles are heavy enough to be carried over long distances and deposited to form dunes. Fine-grained silt and microscopic silica are too light to be carried by wind for long distances, while pebbles and cobbles are too heavy to be lifted by wind in the first place. Therefore, the primary composition of the bedload carried by wind to form dunes is coarse grains of sand.

Deflation in the desert refers to the process of wind removing loose sediment from the surface, creating depressions called blow outs. These blow outs are formed when the wind erodes the finer particles and leaves behind coarser materials such as gravel or pebbles. As the wind continues to remove the sediment, the depression deepens and widens, resulting in a blow out. Therefore, deflation in the desert can lead to the formation of blow outs.

Running water is the main agent that contributes to erosion and weathering in deserts. Although deserts are typically dry, they do experience occasional rainfall. When it does rain, the water quickly runs off the surface due to the lack of vegetation and permeable soil. This runoff can cause erosion by carrying away loose sediment and carving out channels in the desert landscape. Over time, running water can also weather rocks and minerals, breaking them down into smaller pieces. While wind and ice can also contribute to erosion in deserts, running water is the most significant agent due to its ability to transport sediment and shape the land.