Question

Let’s relate food items to magmas of different viscosity; if we compare how honey and water flow when poured from a container: a. then the honey represents felsic magma, and the water represents mafic magma b. then the honey represents mafic magma, and the water represents mafic magma.

Short answer

Option (a): honey represents felsic magma, water represents mafic magma.

Step-by-step solution

Understanding Magma Types

First, let's understand the two types of magma. Felsic magma is rich in silica, making it more viscous, and it flows slowly. Mafic magma has a lower silica content, flows more easily, and is less viscous.

Relating Viscosity to Liquids

Identify which food items have high or low viscosity. Honey has a high viscosity, meaning it flows slowly, whereas water has low viscosity and flows quickly.

Match Viscosity to Magma Types

Now, match honey's high viscosity with felsic magma due to their similar flow characteristics. Conversely, match water's low viscosity with mafic magma.

Selecting the Correct Comparison

Based on the viscosity characteristics, option (a) is correct: honey represents felsic magma, and water represents mafic magma.

Key concepts

Felsic Magma

Felsic magma is a type of magma that is rich in silica, a compound made up of silicon and oxygen. This high silica content makes felsic magma very thick and sticky, similar to honey. Due to its viscosity, it does not flow easily. Imagine trying to pour honey slowly from a jar — it moves sluggishly and tends to stick together. This is how felsic magma behaves when it erupts from a volcano.
When felsic magma cools, it often forms rocks such as granite and rhyolite. These rocks are light-colored, thanks to the minerals like quartz and feldspar present in them.

• Felsic Composition: High in silica, often contains minerals like quartz and feldspar.
• Viscosity: High viscosity due to silica content, making it slower flowing.
• Typical Rocks: Forms rocks like granite and rhyolite.

Understanding felsic magma is essential because its high viscosity can lead to explosive volcanic eruptions, posing significant hazards.

Mafic Magma

Mafic magma, on the other hand, is characterized by having a lower silica content, which makes it much less viscous than felsic magma. It is more similar to water in terms of flow, meaning it erupts more smoothly and quickly from volcanoes.
Picture pouring water from a container; it flows freely and spreads rapidly. This behavior is typical of mafic magma, allowing it to form lava flows that cover large areas.
When cooled, mafic magma tends to form rocks such as basalt and gabbro. These rocks are generally darker in color due to the presence of minerals like pyroxene and olivine.

• Mafic Composition: Lower in silica, includes minerals like pyroxene and olivine.
• Viscosity: Low viscosity allows it to flow easily, much like water.
• Typical Rocks: Results in the formation of rocks like basalt and gabbro.

Understanding mafic magma helps explain how some volcanic eruptions produce large, widespread lava flows that are less explosive than their felsic counterparts.

Silica Content

Silica content is a critical factor in determining the viscosity and behavior of magma. It is composed of silicon and oxygen, forming a network of strong bonds that can affect how the magma flows.
When magma has a high silica content, as in felsic magma, it forms a structure that makes it more resistant to flow. This is why felsic magma is thicker and more viscous. Conversely, mafic magma has a lower silica content, resulting in less resistance to flow and making the magma more fluid.
Silica not only influences the movement of magma but also its cooling characteristics. High silica content leads to slow cooling and crystallization, which in turn contributes to the formation of light-colored, coarse-grained rocks like granite. Low silica content enables faster cooling and typically results in dark-colored, fine-grained rocks like basalt.

• Silica and Viscosity: High silica increases viscosity, low silica allows for greater fluidity.
• Cooling Rates: High silica results in slow cooling and crystallization; low silica allows quick cooling.
• Rock Characteristics: Affects the color and texture of the resulting volcanic rocks.

Understanding the role of silica content in magma helps to predict volcanic behavior and the types of rocks that will form after an eruption.