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Low gas content, common in ______ magmas, contributes to more effusive eruptions.
mafic
The eruption of ______ that began in 1983 is ongoing, an example of an effusive Hawaiian type eruption.
Kilauea
Eruptions of highly viscous lavas may produce explosive clouds of hot ash and gases called ______ columns.
eruption
One type of lava flow is called '______ lava flow', with surfaces of rough jagged blocks with dangerously sharp edges and spiny projections.
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A lava flow may develop a solid upper crust, while the molten lava below continues to advance in a ______ called a lava tube.
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Magmas contain varying amounts of dissolved gases, called ______.
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Magma with high silica content is known as ______ magma
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Magma with lower silica content is known as ______ magma
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Erupted magma is referred to as ______
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Magma generated in the Earth's mantle through partial melting of solid rock occurs in the ______
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Geologists often describe quiescent eruptions as ______ eruptions
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The two primary factors that determine how magma erupts are its viscosity and ______ content
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Geysers occur where extensive underground ______ exist within hot igneous rocks.
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In some regions, groundwater must be treated as a ______ resource because the amount of water available to recharge the aquifer is significantly less than the amount being withdrawn.
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In such situations, groundwater is essentially being ______.
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Treating Groundwater as a Nonrenewable Resource Like many of our other valuable natural resources, groundwater is being ______ at an increasing rate.
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In some areas, overuse threatens the groundwater ______.
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The ground may sink when water is pumped from wells faster than natural ______ processes can replace it.
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Evidences of creep include: Gradual displacement of soil downhill over time. Slowly tilts structures and infrastructure, causing damage. Distorts fences, walls, and other manmade structures. __________
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Solifluction happens when soil is saturated with water, the soggy mass may flow downslope at a rate of a few millimeters or a few centimeters per day or per year. It is also called “soil flow” a type of mass movement that is common wherever water cannot escape from the saturated surface layer by infiltrating to deeper levels. A dense clay hardpan in soil or an impermeable bedrock layer can promote __________.
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Solifluction, a common phenomenon in regions with permafrost, occurs above the permanently frozen ground known as __________.
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Permafrost refers to the permanently frozen ground typical of Earth's tundra and subarctic climates. Solifluction occurs in the active layer, the zone above permafrost that thaws during summer to a depth of about a meter and refreezes in winter. During the brief high-latitude summer, water cannot penetrate the impermeable permafrost layer below, saturating the active layer. The saturated active layer slowly flows downhill due to gravity. Solifluction can occur on slopes as gentle as 2 to 3 __________.
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Solifluction happens when soil is saturated with water, the soggy mass may flow downslope at a rate of a few millimeters or a few centimeters per day or per year. It is also called “soil flow” a type of mass movement that is common wherever water cannot escape from the saturated surface layer by infiltrating to deeper levels. A dense clay hardpan in soil or an impermeable bedrock layer can promote solifluction. Solifluction, a common phenomenon in regions with __________, occurs above the permanently frozen ground known as permafrost.
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Solifluction happens when soil is saturated with water, the soggy mass may flow downslope at a rate of a few millimeters or a few centimeters per day or per year. It is also called “soil flow” a type of mass movement that is common wherever water cannot escape from the saturated surface layer by infiltrating to deeper levels. A dense clay hardpan in soil or an impermeable bedrock layer can promote solifluction. Solifluction, a common phenomenon in regions with permafrost, occurs above the permanently frozen ground known as __________.
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The capacity of rocks to transmit fluid through pores and fractures. Pores must be connected and large enough to allow the groundwater to flow. A rock that does not allow water to flow through it easily is called ______
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Aquifer: A body of saturated rocks or sediment through which water can move easily, such as sandstone, conglomerate, well-jointed limestone, bodies of sand, and gravel. Aquitard: Retard the flow of groundwater. Aqua (water) tard (slow). Poorly permeable. Also known as a ______
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The Movement of Groundwater: Therefore, to ensure a continuous supply of water, a well must penetrate below the water table. Whenever water is withdrawn from a well, the water table around the well is lowered. This effect, termed drawdown, decreases with increasing distance from the well. The result is a depression in the water table, roughly conical in shape, known as a ______
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Scales of Movement: The term artesian is applied to any situation in which groundwater under pressure rises above the level of the aquifer. Wells: The most common method for removing groundwater is to use a well, a hole bored into the zone of saturation. Wells serve as small reservoirs into which groundwater migrates and from which it can be pumped to the surface. The use of wells dates back many centuries and continues to be an important method of obtaining ______
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Pores must be connected and large enough to allow the groundwater to flow. A rock that does not allow water to flow through it easily is called ______. Interaction Between Groundwater and Streams: Aquifer: A body of saturated rocks or sediment through which water can move easily, such as sandstone, conglomerate, well-jointed limestone, bodies of sand, and gravel. Aquitard: Retard the flow of groundwater. Aqua (water) tard (slow). Poorly ______
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Aquifer: A body of saturated rocks or sediment through which water can move easily, such as sandstone, conglomerate, well-jointed limestone, bodies of sand, and gravel. Aquitard: Retard the flow of groundwater. Aqua (water) tard (slow). Poorly permeable. Also known as a ______. The Movement of Groundwater: Therefore, to ensure a continuous supply of water, a well must penetrate below the water table. Whenever water is withdrawn from a well, the water table around the well is lowered. This effect, termed drawdown, decreases with increasing distance from the well. The result is a depression in the water table, roughly conical in shape, known as a cone of ______
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