Volcanoes
Week 7-Earth Science
Mapping Volcanoes Lab
The Law of Superposition
“The oldest layers are on the bottom”
Relative Age (vs. Exact Age)
How old something is in relation to another object.
“Younger”
“Older”
“About the same age as…”
Cross-cutting Relationships
The feature “being cut” is older than the feature cutting through it
Superposition Relationships
Younger features are on top of older features
NASA’s Earth Observatory-July 11, 2022
“Idaho is the top potato producing state in the United States. Almost one-third of the nation’s potatoes are grown in the Snake River Plain, a belt of low-lying land that extends across southern Idaho.
The eastern part of the Snake River Plain likely formed when the North American tectonic plate drifted over a hot spot in Earth’s crust. Basaltic magma was injected into the crust, making it thicker and denser than surrounding areas. When the crust cooled and settled, the land sank. The same hotspot that created the plain now fuels the geysers in Yellowstone National Park, located just northeast of the plain. The western part of the plain is a graben—a piece of land that has sunk between parallel faults in the Earth’s crust.”
Evidence of this volcanic activity can be seen in these natural-color images, which show fingers of basaltic lava reaching into farm fields. The 5,000-year-old lava field, called Hell’s Half Acre, resembles a flat moonscape with sparse vegetation.
This image, acquired on July 11, 2022, with the Operational Land Imager (OLI) on Landsat 8, shows a detailed view of the lava and farm fields around Idaho Falls.
The injection of volcanic materials makes soils in the plain especially fertile for crop production, but the area receives only about 20 to 30 centimeters (8 to 12 inches) of precipitation a year. Potatoes are especially sensitive to drought and center-pivot irrigation is supporting many of the potato fields, as indicated by the green crop circles standing out from barren ground.
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Lava Characteristics
Volcano types
Igneous Rock Types
Lava Types
A’a
has a rough, jagged, spiny surface
Pahoehoe
characterized by a smooth, billowy, or ropy surface
Velocity
The speed and direction something is moving
Viscosity
“Resistance to flow”
Photo Homework Idea!