Question

Fill in the blanks with the correct vocabulary word or words. A broad volcano with gently sloping sides is called a(n) __________.

Short answer

A broad volcano with gently sloping sides is called a shield volcano.

Step-by-step solution

Understanding the Question

The question is asking about a type of volcano that is characterized by its broad base and gently sloping sides. Our task is to identify the specific term that matches this description.

Identifying the Vocabulary

We need a term related to types of volcanoes. Characteristics described are 'broad' and 'gently sloping sides'. In geology, a volcano that fits these characteristics is known as a 'shield volcano'.

Confirming the Answer

Cross-verify that 'shield volcano' is indeed the name of the volcano type described. A shield volcano is formed by low-viscosity lava flows of basaltic type and is known for its wide, shield-like profile, confirming it matches the given description.

Key concepts

Types of Volcanoes

Volcanoes are fascinating geological features that come in various shapes and sizes. One of the primary types of volcanoes is the shield volcano. Shield volcanoes are known for their broad, shield-like shape and gentle slopes. This shape is formed due to the lava's properties they eject. Unlike other types, such as stratovolcanoes and cinder cones, shield volcanoes produce a long-lasting but usually less explosive type of eruption. Other types of volcanoes include:

• Stratovolcanoes: Steep, conical volcanoes composed of layers of hardened lava and ash.
• Cinder Cones: Smallest type, with steep sides, typically formed around a single eruptive vent.
• Lava Domes: Formed by slow eruptions of viscous lava.

Understanding the different types of volcanoes and their formations helps us appreciate the diversity of volcanic structures on Earth and predict their potential hazards.

Volcano Structure

When it comes to understanding volcanic structures, one must consider what lies beneath the impressive towering forms. A volcano has several key parts:

• Magma Chamber: A reservoir of molten rock beneath the Earth's surface.
• Vent: An opening through which lava, ash, and gases are expelled.
• Crater: The bowl-shaped depression around the main vent.
• Caldera: A larger depressed area formed when a volcano collapses into its magma chamber.

Shield volcanoes, in particular, boast large vents and extensive magma chambers. Their structure allows for the continuous flow of lava, which explains their gentle profile. This vast distribution of lava layers results in a broad base, creating a shield-like appearance.

Geology

Geology plays an essential role in understanding why and how volcanoes form. It examines the Earth's physical structure and the processes that have shaped it over millions of years. Volcanoes, including shield volcanoes, arise from tectonic activities involving the Earth's lithosphere. When tectonic plates diverge or converge, magma from the mantle pushes through the Earth's crust, leading to volcanic eruptions.
Shield volcanoes are primarily found at divergent plate boundaries and hotspots. Studying lava flow patterns and volcanic rocks can provide insights into past volcanic activity. This geological understanding helps scientists predict future eruptions and mitigate associated risks.

Basaltic Lava

Basaltic lava is the primary lava type associated with shield volcanoes. This type of lava has several distinctive features:

• Low Viscosity: Flows easily, allowing it to travel long distances over flat terrain.
• Mafic Composition: Contains higher amounts of magnesium and iron, giving it a dark color.
• Rapid Cooling: Forms basalt, a dense rock, upon cooling.

The low viscosity of basaltic lava is crucial in forming the gently sloping structure of shield volcanoes. As this lava flows and cools, it builds up the extensive and broad profiles characteristic of shield volcanoes. Understanding basaltic lava's properties allows geologists to predict the flow patterns and potential impact of eruptions.