Geoscience of National Parks Exam 3

Utah State Univeristy

What is the heat source fueling the Yellowstone Caldera?

The continental Yellowstone Hot Spot

How was the Snake River Plain Volcanic Province formed?

Formed as the North American Plate moved southwest over a stationary hot spot, leaving a trail of older calderas.

What are the characteristics of the land surrounding Yellowstone?

Volcanic plateau, high elevation, cold climate, active hydrothermal systems, unique ecosystems, and uplifted terrain.

What type of volcanic rocks dominate Yellowstone and why?

Rhyolitic rocks dominate due to silica

What eruptive material is most common in Yellowstone?

Tuff and other pyroclastic deposits.

What is the composition of lava in Yellowstone and dominant rock type?

Silica - dominant rock is rhyolite.

What are the magma trends in Yellowstone?

High silica content, high viscosity, relatively lower temperature, highly explosive eruptions, produces rhyolite and tuff.

What does Craters of the Moon National Monument highlight and where is it located?

A volcanic landscape on the Snake River Plain east of Idaho Falls.

What volcanic features are found at Craters of the Moon?

Cinder cones, ʻaʻā and pāhoehoe lava flows.

How were the Craters of the Moon features formed?

Rift/fissure eruptions triggered by normal faulting.

How many geysers are in Yellowstone?

Over 500 geysers.

What drives geothermal activity in Yellowstone?

Heat from the hotspot below

Why are some geysers predictable and others not?

Some have a steady recharge of heat and water. The pressure is constantly building up until the steam is released from the geyser

What is sinter and its composition?

Lightweight deposit of silica formed by precipitation from hot springs and geysers.

How does sinter form?

Silica precipitates as hot water cools at the surface.

How is sinter different from travertine?

Sinter is silica and travertine is calcium carbonate-based.

What bedrock is involved in travertine formation?

Limestone that dissolves and reprecipitates as calcium carbonate.

What causes rainbow colors in hot springs like Grand Prismatic Spring?

Heat-loving microbes form colorful mats based on temperature gradients.

Which indigenous cultures lived in Yellowstone?

Various Native American tribes such as the Shoshone and Crow.

Who established Yellowstone as the first U.S. National Park?

President Ulysses S. Grant.

What happened during the Precambrian in Yellowstone?

Formation of basement rocks about 2 billion years old.

What characterizes Paleozoic rocks in Yellowstone?

Marine sedimentary rocks.

What characterizes Mesozoic rocks in Yellowstone?

Continental sedimentary rocks from rivers, dunes, and floodplains.

What characterizes Cenozoic rocks in Yellowstone?

Mountain building and volcanic activity.

What built the Yellowstone Plateau?

Absaroka volcanics and later caldera eruptions.

What are the three major Yellowstone eruptions?

Huckleberry Ridge (~2.1 Ma), Mesa Falls (~1.2 Ma), Lava Creek (~670 ka).

What is a Yellowstone style caldera?

A large volcanic depression formed after massive eruptions and collapse.

What is a supervolcano?

A volcano capable of eruptions exceeding 1,000 km³ of material.

How does a Yellowstone caldera erupt?

Magma upwelling, ring fractures, explosive eruption, chamber empties, collapse occurs.

What are the three “stories” of Cache Valley?

Rocks were formed at sea level and raised due to tectonics. The Laramide and Sevier orogenies caused the mountains to elevate and fold. A deep lake filled Cache Valley and created the delta upon which USU is built.

What types of faults are involved in Cache Valley geology?

Reverse/thrust faults from compression and normal faults from extension.

What physiographic province is Grand Teton National Park in?

Rocky Mountain region.

How did the Teton Range form?

Movement along the Teton Fault.

What type of fault is the Teton Fault?

A normal fault caused by extension.

How did movement on the Teton Fault create the range?

The range was uplifted while the valley dropped down.

How old are the Teton Mountains versus their rocks?

The rocks are about 2.5 billion years old, and the mountains are 6–10 million years old

What rocks are found in Grand Teton National Park?

Metamorphic gneiss and granite

What is tuff and where did it come from?

Volcanic ash rock from Yellowstone eruptions.

What type of mountain range is the Sierra Nevada?

Tilted fault-block

What is the Sierra Nevada’s relation to the Basin and Range Province?

It forms the western boundary.

What is the general geologic history of Yosemite?

Subduction formed a batholith, later uplift and erosion exposed it.

What is a batholith?

A large intrusive igneous body made of granite.

What minerals are in Yosemite granite?

Quartz, feldspar, and mica.

How old are the granitic rocks in Yosemite?

Mesozoic, over 100 million years old.

How did Yosemite’s domes form?

Exfoliation due to pressure release as the overlying rock is removed

What is a roof pendant?

A remnant of older rock sitting on a batholith.

What carved Yosemite Valley?

Glacial activity.

Is Yosemite still rising tectonically?

Yes, due to ongoing uplift.