Chapter 9 Vocabulary Quiz

A large, crater-shaped basin formed after the top of a volcano collapses is called a caldera. This occurs when the magma chamber beneath the volcano empties during an eruption, causing the volcano to collapse inward. The resulting depression is usually much larger than the original volcanic crater and can span several kilometers in diameter. Calderas are often characterized by steep walls and may contain hot springs, geysers, or even lakes. They are significant geological features that provide insights into the volcanic activity and history of an area.

A cone-shaped volcano formed by the accumulation of lava fragments that have been ejected from a volcanic vent is referred to as a cinder cone volcano. These volcanoes are typically small in size and are composed of loose, fragmented volcanic material known as cinders. The explosive eruptions from the vent result in the deposition of these cinders, forming the characteristic cone shape. Cinder cone volcanoes are often found in volcanic fields and are associated with basaltic lava flows.

A volcano made of layers of hardened lava flows and pyroclastic materials is called a composite volcano. This type of volcano is characterized by its steep slopes and a conical shape. It is formed by alternating eruptions of lava and explosive eruptions of ash, cinders, and other volcanic materials. The layers of hardened lava and pyroclastic materials build up over time, creating the composite structure of the volcano.

A hot spot is an area of volcanic activity that occurs when a plume of hot solid material rises from deep within Earth's mantle. This plume creates a localized region of intense heat, causing volcanic eruptions and the formation of volcanic features such as islands or seamounts. Hot spots are stationary, unlike tectonic plate boundaries, and can be found in various locations around the world, such as Hawaii or Yellowstone National Park.

A fast-moving mudflow that occurs when the heat associated with a volcanic eruption melts snow and ice on top of a volcano is called a lahar. Lahars are highly destructive and can travel at high speeds, carrying large amounts of debris, rocks, and mud downhill. They can cause significant damage to infrastructure and pose a threat to human lives and property in volcanic regions.

Viscosity refers to a substance's resistance to flow. It is a measure of the internal friction within a fluid, determining how easily it can be deformed or moved. Substances with high viscosity, such as honey or molasses, flow slowly, while substances with low viscosity, like water or gasoline, flow more easily. Therefore, viscosity accurately describes a substance's resistance to flow.

Magma that reaches the Earth's surface is called lava. Lava is the molten rock that flows out of a volcano during an eruption. When magma is expelled from the Earth's interior and comes into contact with the atmosphere, it cools and solidifies, forming solid rock. Lava can have different textures and compositions depending on the type of volcano and the minerals present in the magma. It is often associated with volcanic activity and can cause destruction and create new landforms when it flows and cools.

A plateau formed from basaltic lava pouring from a crack or fissure in Earth's surface is called a lava plateau. This type of plateau is created when large amounts of basaltic lava flow out of the Earth and spread over a wide area, creating a flat or gently sloping surface. Over time, the lava cools and solidifies, forming a hard and resistant layer that can withstand erosion. Lava plateaus are often found in areas with extensive volcanic activity and can cover vast regions, such as the Columbia Plateau in the United States or the Deccan Plateau in India.

Pahoehoe is a term used to describe a type of solidified basaltic lava flow on land that has formed with smooth, rope-like surfaces. This type of lava flow typically has a low viscosity, allowing it to flow easily and form these distinctive features. The term "pahoehoe" comes from the Hawaiian language, where it is commonly used to describe this type of lava flow.

Lava that cools under water forms a distinctive pillow-like shape due to the rapid cooling and solidification of the outer layer of lava, while the inner lava continues to flow. This results in the formation of rounded, pillow-shaped structures known as pillow lava.

A dense superheated cloud of gases and pyroclastic materials that moves rapidly downhill from an erupting volcano is referred to as a pyroclastic flow. This phenomenon occurs when volcanic ash, rocks, and gas are ejected from the volcano and flow rapidly down the slopes due to gravity. Pyroclastic flows are extremely dangerous and can reach speeds of hundreds of kilometers per hour, causing widespread destruction and posing a significant threat to human life and infrastructure in the surrounding areas.

A volcano with a broad base and gently sloping sides is called a shield volcano. This type of volcano is characterized by its low viscosity lava that flows easily and covers a large area, creating a shield-like shape. Shield volcanoes are typically formed by multiple eruptions of fluid basaltic lava, which gradually build up the volcano over time. They are known for their relatively calm eruptions and are commonly found in hotspots and along mid-oceanic ridges.

A volcano is an opening in the Earth's crust through which molten rock, gases, and ash erupt. It is also the landform that develops around this opening. Volcanoes can form mountains or hills and are often characterized by a cone-shaped structure. They occur due to tectonic activity and the movement of magma beneath the Earth's surface. When the pressure builds up and the magma erupts, it can cause explosive eruptions or more gentle lava flows. Volcanoes are important geological features that play a significant role in shaping the Earth's surface and influencing the environment.

Pyroclastic material refers to solid rock fragments that are forcefully expelled during a volcanic eruption. These fragments can vary in size, ranging from tiny ash particles to larger rocks and boulders. They are propelled into the air at high speeds due to the explosive nature of the eruption. Pyroclastic material can cause significant damage and pose a serious threat to human life and infrastructure. It can also contribute to the formation of volcanic ash clouds and pyroclastic flows, which are deadly fast-moving currents of hot gas, ash, and rock fragments.

The correct answer is "aa." A solidified basaltic lava flow on land that has formed rough, jagged surfaces is called "aa." This type of lava flow has a blocky texture and is characterized by sharp, angular fragments. It is formed when the outer surface of the lava flow cools and solidifies, while the interior continues to flow, causing the surface to break apart into rough, jagged pieces.