Windows to the Earth
Chapter 1
A Land of Scenery and Violence
1959 Earthquake
11:37 pm
6.3 - 7.5
160 geysers erupted at the same time
100s of springs turned muddy
Landslides made the wind so strong that it ripped people's clothes off
Set loose boulders the size of houses
30-foot tsunami
28 deaths
Dozens injured
A hotspot for disaster
Earth's crust is being stretched by basin and range formation
Strongest quakes in the Mountain West
Vertical plume of magma 125 miles deep
Ongoing for 16.5 million years
Teton- Yellowstone combo seen nowhere else in the world
The geology here is “a living entity”
Yellowstone shaped the West
Largest hotspot under any continent
Among the largest of any hotspot on earth (30 or so)
1 inch of movement per year
100 eruptions over the last 16.5 million years
Formed chains of calderas 500 miles long
Starting at the Idaho, Oregon, and Nevada border
Between 7 and 13 “volcanic centers”
Like Yellowstone and the 3 calderas is a volcanic center
300-mile 1,700-foot bulge
Post-eruption 2,000-foot sinking
Subsequent basalt flows help to create nutrient-rich soils
3 Yellowstone eruptions
2.1 million years ago, the Huckleberry Ridge eruption
2,500 times larger than Mt. St. Helens
1.3 million years ago Mesa Falls eruption
280 MSHs
631,000 years ago, the Lava Creek eruption
1,000 MSHs
Many folks are surprised by the lack of mountains in YNP
Legacy of the hotspot
The current caldera is 30 miles by 45 miles
30 lava flows obscure the actual caldera
The most recent lava flow was 70,000 years ago
Recognized by Hayden in 1871
30-40 times more heat comes off the earth inside the caldera than is typical elsewhere
A column of hot and molten rock under the earth
At least 50 miles deep
Heats the overlying rock
3-8 mile deep magma chamber
Produces 500-1000 geysers
Geysers owe their existence to the high number of earthquakes
YNP breathes
Typical of calderas
Occasionally burps lava
Fairly rare event
It is impossible to predict so far
Burn, Freeze, Shake, and Slide
Volcanic soils foster lodgepole pines
300-year fire cycle
Glacial maxima
Yellowstone ice field ~3,500ft thick
Covered both Yellowstone and Grand Teton National Parks
Deepened Yellowstone and Jackson Lakes (1,800ft)
Massive floods as glaciers receded
Downcut many valleys
Earthquakes are the dominant force on human time scales
1959 Hebgen lake
1983 Borah peak, ID (7.3)
None along the Teton fault in historic times
1925- 4.0 in Jackson Hole
Triggered the Gros Ventre slide
250 million tons of earth moved
1927 earthen dam burst
6 people killed
The Teton and Wasatch faults are the most dangerous
Capable of a 7.5
Both are “overdue”
A night of terror
Madison landslide
80 million tons of earth
Enough to pave a 6-lane highway from Bozeman to NYC 1 foot deep
Hebgen quake (~7.3)
Hebgen scarp 22 feet by 8 miles
Red Canyon Scarp 22ft by 14 miles (other side of the fault block)
Tilted huge block or rock
Dropped one side of the lake 19 feet
Created a seiche
20-foot wave every 17 minutes
Went on for 11 hours
5 aftershocks within 10 hours
Between 5.5-6.3
Created Earthquake Lake
5 miles long
150 feet deep
Chapter 2
In the Wake of the Yellowstone Hotspot
I15 or I84
Flat, sagebrush, and basalt
Mountains once ran through the region
50-mile-wide valley
“Snake River Plain”
Created by a hotspot, it resembles a boat wake
What are hotspots?
Earth Layers
Crust- brittle
Oceanic crust: thin, 6 miles thick
Continental crust
Thicker, 30+ miles thick
Mantle
Denser than the crust
Extends 1,800 miles to the core
Lithosphere
Top 50-80 miles
Includes crust and upper mantle
Brittle
Compose the “tectonic plates”
The Pacific plate slides northwest at 2 inches per year
Juan de Fuca Plate
Subducting
Oregon, Washington, and British Columbia
Forms the cascade range
Convection drives plate movement
Lithosphere floats on “hot plastic”
Hotspots raise large volumes of hot molten rock
“Mantel plumes
1,800 miles below at the mantle/core boundary
Seismic tomography
100s of seismometers measure the speed of sound/ shock waves
Travel more quickly through cold, dense rocks than warm ones
The shallow hotspot hypothesis says spots originate 125 miles below the surface
Radioactive decay creates core heat
Fluid dynamics brings the hottest magma to the surface
Magma pools 50 miles below the crust boundary
Heats overlying rock (melts it)
Rhyolitic magma = thick and viscous
Basaltic magma = thin and runny
The magma plume only partly melted
3-8 miles below the surface
Hotspot of the Solar System
30 hotspots in the world
All under the oceans except Yellowstone
Similarities to oceanic hotspots
Earth bulge
300-mile-wide bulge
Differences
Thicker, older, and colder crust
Crust richer in silica
Rhyolite is 1,000,000 times more viscous
Tremendous gas pressure builds up
Can still occasionally erupt basalt
Venus has hotspots
Their hotspots move
Challenges previous knowledge of an inactive core
Io, Jupiter's moon, has 30 hotspots
Hyper-active plates
Olympus mons
Widespread hydrothermal on Mars!
Before the Hotspot
20 million years ago- basin and range accelerated
17 million years ago, the first supereruption
13 million years ago, the modern Teton fault
2.1 million years ago, the first supereruption
570 million years ago, Precambrian
Flooding by a shallow sea 245 million years ago
3.4- 3.8 billion years ago, Beartooth and Wind River rocks formed
Teton rocks
2.4 billion-year-old gneiss
2.8 billion-year-old granite
1.5 billion-year-old diabase dikes
535 million years ago, Flathead Sandstone
Yellowstone National Park
360-320 million years ago, Madison Limestone
Mesozoic 245-66 million years ago
Triassic rocks reddish
Dinosaur spot in the GYE
The Cretaceous was a shallow sea
hydrocarbon/ coal
Sevier orogeny
1st mountain building episode
110 million years ago
Laramide orogeny
80 million years ago
The Rocky Mountains formed
Continued to the Cenozoic
<66 million years ago
50 million years ago, the Absoroka formed
Large volcanic eruptions
30 million years ago
West began stretching East to West
Accelerated 17 million years ago
Continues today
Modern “basin and range” formation
The Ancestral Teton Fault formed 34 million years ago
16.5 million years ago, the Yellowstone hotspot emerged
Origins of Yellowstone Hotspot
Mendocino triple junction
Northern California coast
North American, Pacific, and Gorda plates
Which came first
Stretching or Hotspot
Traditional Hotspot Theory
Originates at the core-mantle boundary
New Hotspot Theorgy
125 miles below the surface
Formation related to surface features
Columbia River basalts
17-6 million years ago
Formed the Columbia River Gorge
100 caldera-forming eruptions
16.5 million years span
Outpourings from Hell
Colossal caldera-forming events are fed by magma chambers
Large, sponge-like bodies of molten and partially molten rock in the crust
Known as plutons
Greek god of the underworld
45 miles by 30 miles
Same as the overlying caldera
When it solidifies, it is called a batholith
Fluid and gas pressure bring magma to the surface
During an eruption
Debris is hurled at supersonic speeds
Magma is pulverized by the sudden expansion of gas bubbles
Nearly instantaneous turns into ash, pumice, and bombs
Lava flows
60 miles in all directions from the caldera
Ash falls
500 miles radius
1 foot of ash
The caldera
45 miles by 30 miles, 600 feet deep
Destroyed mountain ranges
Older calderas
Little is known
Covered by large basalt flows
12 million years ago
Ash killed large numbers of animals as far as Nebraska
Track of the Hotspot
Rhyolite rocks along the entire length
100 distinct ages
7 Volcanic centers
McDermitt Volcanic Field
16.5 million to 15 million years ago
Owyhee Volcanic Center
15-13 million years ago
Bruneau-Jarbridge
12.5-10.5 million years old
Outside of Boise
Twin Falls Caldera
10.5-8.6 million years old
Picabo
10-7 million years old
Blackfoot, ID
Heise Volcanic Center
6.5, 6, and 4.3 million years old
North of Idaho Falls
Big Bulges
“Topographic swell”
Molten rock buoyancy
400-900 miles possible
Yellowstone 400 miles
Contributed to a 3,500ft ice cap
When the hotspot left the Snake River Plane it sank 2,000 feet
Basalt flows are the last stage of volcanism
Contributes nutrients to the rich Idaho soil
Quakes in the Wake
Snake River plane
The most geologically active area in the West
30 >5.5 quakes since 1900
This volcano doesn’t create mountains it destroys them
Left plains adjacent to mountains
The hotspot's last stage
Seismic tomography looks deep into the Earth
Snake River plane is covered 1 mile deep in iron-rich basalt
3 stages of volcanism
“Pre-Yellowstone”
125-mile-deep hotspot
Radioactive decay heat source
Magma pools 25-50 miles deep
Causes the ground to bulge
“Yellowstone stage”
Molten basalt sheared off the hotspot
Via plate movement
Blobs rise to the surface
Melts surrounding rhyolite
Molten rhyolite rises
Pressure decrease in the rock
Gases in rock expand
Boom! Explosive eruption
Pyroclastic flows
Magma chamber empties
Collapses downward
Each major eruption is followed by smaller rhyolite flows
“Post caldera eruptions”
Snake River Plain Stage
Rhyolite chamber cools
Allows basalt to rise
Less gas and less viscous
Non-explosive
Landscape smoothes
Hotspot moves away
Land mass sinks
Remaining rocks (top to bottom)
Gentile rhyolite flows
Rhyolite tuff
Iron-rich slag
Total volume of basalt 2-3 times caldera-forming eruptions
Chapter 3
The Hotspot Reaches Yellowstone
Epicenters
Earthquakes occur along 2 parallel lines
SE to NE
First Yellowstone Eruption
2.1 million years ago
50 by 40 miles
Rhode Island-sized hole in the ground
Pumice and ash piled up and welded themselves together
600 cubic miles of ash
Mt. St. Helens ¼ cubic mile
2,500 times larger
Some estimate 8,000 times larger
Tuff is denser than ash
Enough to bury Wyoming 38ft deep
Second Eruption
1.3 million years ago
Island Park Caldera
15-mile wide hole
67 cubic miles of rock
Most recent eruption
631,000 years ago
45 by 30-mile hole
1,000 times larger than Mt. St. Helens
245 cubic miles of debris
Volcanism on a Grand Scale
Largest known center of active volcanism on any continent
As opposed to on the ocean bottom
Mammoth Lakes is ¼ as large as Yellowstone
Yards of ash covered Minnesota, Iowa, Missouri, and parts of Mexico
Basalt flows as recently as 200,000 years ago
Rhyolite flows less than 70,000 years ago
Rocks from Volcanic Ash
Hot ash fell and hardened into Tuff
Huckleberry Ridge tuff 500-2,500 ft thick
~800 at the south entrance
Secondary eruption
500ft thick Mesa Falls Tuff
Third eruption
Lava Creek Tuff is 1,600 feet thick
The floor collapsed 1,000 ft
Lava flowed from fault edges
The north side of Madison Canyon is the caldera edge
Going with the Flow
Each eruption is followed by smaller explosive eruptions
The largest was 50 times larger than Mt. St. Helens
~30 lava flows composed of rhyolite
The Upper Geyser Basin exists because of the surrounding lava flows
The edges of the caldera produce most lava flows
Extensional faulting
1.3 million-year-old columnar basalt at calcite springs
The Domes: Resurgent Yellowstone
2 domes
Started as hills of rhyolite
Sour Creek dome
Older of two (600,000 years)
6 by 10 miles
6 miles north of the Fishing Bridge
Mallard Lake dome
150,000 years old
7 by 5 miles
The presence of grabens on each suggests upward expansion
Duel conduits give caldera its elongate shape
Hot water and steam eruptions
Hydrothermal eruptions
Create phreatic craters
Chapter 4
How Yellowstone Works
“Active, breathing, volcano”
Has reshaped the landscape of 25% of the US
Heat is Yellowstone's driving force
Conduction: hotter rocks warm colder rocks
~25% of the heat
Connection: hot water movement
~75% of the heat
Drives geysers
The hottest borehole temperature is 460 degrees F
5 gigawatts per day
Enough to power 2 million homes
No oil near YNP
Heat has degraded it
Hot rocks in the Earth's crust
rocks are less dense than elsewhere
Highly fractured
Data gathered by tomology
Speed of seismic waves in rock
3,000 to 6,000-foot-deep rhyolite top
Sediment capping it
Pluton extends from 3 to 8 miles below
Only 20%-30% molten
Fractured rhyolite acts like a sponge
Geysers and Hotsprings
“The place where hell bubbled up”
Jim Bridger
“Geysir” is Icelandic for gushing
Located where groundwater can easily sink into the ground
Valleys between lava flows
Active faults
Caldera rim fracture zone
Once a geyser starts erupting, it is self-perpetuating
Old Faithful
2’ x 5’ at the surface
4” constriction below
2-5 minute eruptions
244°F below the surface
8,500 gallons of water
Hot springs occur when water isn’t trapped or pressurized
Fumaroles are steam vents only
Acidic water
Dissolved pants of people sitting on damp ground
Ground sounds hollow
Geyserite deposits and sinter made of silica and opal
Mammoth travertine
Calcium carbonate
Thermus aquaticus
Discovered in the mid-1960s
Thomas Brock was the discoverer
Kerry Mullis used it in the mid-1980s
Used Taq Polymerase to speed up the PCR reaction
1993 Nobel Prize
Earthquakes in Yellowstone
Hayden expedition in 1871 had “Earthquake Camp”
Along Yellowstone Lake
800 x 120-mile intermountain seismic belt
YNP is 1% of the belt
Provides 20 percent of the energy
1st seismographs in the early 1970s
Basin and Range Earthquakes
Sierra Nevadas to Wasatch
Stretching creates normal faults
Creates dramatic mountains
Volcanic Earthquakes
Often swarm quakes
Similar size and locale
Many small earthquakes
Earthquakes in the caldera are smaller than those outside
<5.0
Shallower inside the caldera
2 miles vs 10-12 miles
Geysers need earthquakes
Old faithful times changed
1959- 7.2 Hebgen Lake quake
1983- Borah Peak, ID
1998- small quake storm in YNP
Constant cracking of the Earth's crust allows corridors for water to reach the surface
The shifting shoreline
The western half of the lake is in the caldera
5 terraces on the lake shore
Each from a different lake level
Old benches
1,000 years each
Caldera bulges up and edges sink
Huffs and puffs from the Caldera
1970s trees on the south shore were inundated by water
Caused by the rise of Caldera
Up 30 inches 1923-1972
Up 10 inches 1970-1984
Down 8 inches 1985-1995
Rise and fall caused by deep magma movement
The broken earth
Why the Tetons Are Grand
The Teton Fault
A few thousand 7-7.5 earthquakes in the past 13 million years
Usually 3-6 feet of movement
23,000 feet of offset in 13 million years
2.8 billion-year-old Gneiss and Schist
2.4 billion-year-old granitic rocks
Displaced by 33,000 feet
Last magnitude 7+
4,840-7,090
“Overdue”
Trios Tetons
Coined by French-Canadian Trappers
“He must of been of a most susceptible nature, I would fain believe, long a dweller amid those solitudes, who could trace in the cold and barren peaks any resemblance to a woman's bosom”
Nathaniel Langford 1869
Many trappers until the 1830s
Trade collapsed
The National Forest was created in 1908
Most turned into a national park in 1929
Jackson Hole National Monument 1943
Full National Park created in 1950
Topography of the Tetons
40 miles by 15 miles
Steep on the eastern face
Gentle on the western face
Jackson Hole
10 miles by 50 miles
Basement rock tilted 45*
10 miles below the surface at the base of the Tetons
Glaciation up to 14,000 years before present
A drop of the floor twice the distance of the uplift
Faulted earth, flowing water
High peaks east of the continental divide
Very unusual
Eastern slopes have very powerful streams
Valley floor slopes ~1* west
Jackson Lake
16 miles long
Drains east despite the western slopes
Moraines
Birth of a Fault
13 million years ago
Rocky Mountains
80-30 million years ago
Compression by colliding plates
Created thrusts and overthrust faults
Gentle 30* slopes
Wyoming Overthrust Belt
Stocks folded and pushed over each other
Trapped oil and gas
34 million years ago
Gros Ventre and the Tetons were connected as a high plateau
The Farallon plate fully subducts
The relative motion of the North American and Pacific plates shifts to N/S movement
Allows extensional faulting
Basin and Range formation
200 miles of crystal stretching
Normal fault every 15-2-0 miles to the eastern sierras
The Basin and Range started 17 million years ago
The Teton fault is younger than that
Colter formation 15-17 million years ago
Lake sediments
Angular unconformity with the Teewinot formation
Marks the fault activation around 13 million years ago
Modern Earthquakes
No major earthquakes in historic times
Mild-moderate earthquakes in the 1900s-1930s
No northern quakes in historic times
Shaking, Sliding, and Flooding
The Gros Ventre slide was caused by an earthquake
In addition to the wet spring and summer
May 18th is the same as Mt. St. Helens
50 million cubic yards of rock
2,100ft x 2000ft x 225ft
Slide Lake
3 miles long
The upper 50 feet failed in 1927
6 feet of water through Wilson
$500,000 in damage ($8.8 million in 2023 money)
Volcanism in the Tetons
Uplift causes deviation
9 million years ago
Volcanics in Southern Tetons
4 million years ago, “Conant Creek” tuff
Signal mountain
2 million years ago, Huckleberry Ridge Tuff
Track fault movement
Timing of Big Earthquakes
Huckleberry Ridge Tuff is 13,000ft higher than parts of Jackson Hole
6feet every 900 years
7.0+ every 3,400 years
Most recent 7,100 to 4,800 years ago
9 Scarps between 14,000 and 4,800 years ago
Earthquakes occur at different rates at different parts of the fault
The average of 2,000 years in between major earthquakes
Earthquakes don’t occur at consistent rates
Basin and Range will continue
It could be a dormant fault at this point
Chapter 6
Ice over Fire
“Glaciers carve the Landscape.”
The last big glaciers retreated 14,000 years ago
On each major ice age, 3,500-foot-thick ice caps formed over Yellowstone
Ice helped sculpt the Grand Canyon of the Yellowstone
Helped sharpen the Teton spires
Melting ice flooded streams and rivers
Cut terraces along the Snake River
What are Glaciers?
Large, moving masses of ice
Formed when snow accumulates winter after winter and is compressed to form ice
Temperatures remain cool enough through the year to not fully melt last year's snow
Grow in cool times and retreat in warm times
Large masses called ice caps
Whole mountain ranges
Smaller masses called “alpine glaciers”
Boulders, rocks, gravel, sand, and flour become trapped in ice
Rock flour suspended in water gives a turquoise appearance
The Big Chill- “The Pleistocene Epoch”
1.6 million years ago to 10,000 years ago
Average 7*F cooler
Continental ice sheet
Did not reach YNP
YNP is covered by a large ice cap
2 Major Glacial Periods on Earth
600-800 million years ago
200-300 million years ago
Complicated causes
What produces large-scale glaciation?
Ocean currents, continental arrangement, orbit, rotation, and tilt
No definitive cause for the Pleistocene
A volcanic eruption is too short-lived
A Land of Fire and Ice
10 known hydrothermal explosion craters in YNP
Some with glacial debris
Lava flows up to 70,000 years ago
1,700 feet of uplift
YNP chilled 8°F
Time of Glaciers
3 major glaciations
Non-consensus on the dates
Buffalo Glaciation
2-1.3 million years ago
Little known
Bull Lake Glaciation
125,000- 45,000 years ago
10+ glacial advances and retreats
More extensive than previous ages
125 miles of ice
Covered from Absorokas to South Park
Debris covers Signal Mountain
Pinedale Glaciation
50,000 - 14,000 years ago
Best known
3,500-foot ice cap (10,500 feet altitude)
80 miles North to South by 60 miles East to West
Lasted until 12,000 Years ago
Started retreating 14,000 years ago
Today
11 small glaciers remain
Remnants from the Little Ice Age
1400s to 1800s
A River Runs Through It
Glaciers retreated
Flood waters released
Outwash plains pocked by “kettles”
Pothole depressions
140-foot terraces in Jackson Hole
Birth of the Big Lakes
Jackson Lake
13 Million Years ago
Glacially carved
16 miles by 6 miles
437 feet deep at the base of the mountains
800-foot trough gouged by lice
Glacial moraine diverted the Snake River to the east of Signal Mountain
100-300 foot tall
Yellowstone Lake
2 million years ago
20 miles by 13 miles
3 basins
325 East Side
200 South Arm
280 west thumb
Most of the lake was formed from volcanism
631,000 years ago
LeHardy rapids are located along multiple faults
The South and Southeast arms are glacially carved
Chapter 7
Future Disaster
“The greatest laboratory that nature furnishes on the surface of the globe”
The complex relationships among Yellowstone National Park flora, fauna, and geology helped inspire America’s budding conservation ethic
The idea of GYE recognizes that its living and geological wonders extend beyond the boundaries of the park
GYE is roughly defined by a 6,100-foot boundary
Critical to temperature and moisture
Expansive lodgepole pine due to rhyolitic soils
Grizzly forage patterns predicted by soil geology
Trout jacuzzis in Lake Yellowstone
Volcanic minerals foster plant growth in the Firehole
Greater Yellowstone Geoecosystem
Nightmare on the Teton Fault
When the fault ruptures again, it will be a worst-case scenario
Violent shaking
30+ seconds
Landslides along the Teton Range
12-foot-tall cliffs will pop into existence
Streams and rivers will be blocked
Jackson dam failure
6ft or larger waves across Jackson Lake
5 hours until the water hits Moose, WY
Betting on Seismic Disaster - Teton Fault
Major quake every 680-4,000 years
Most recent quake 4,840- 7,090 years
Capable of a 7.0+ quake
5 faults capable of such in GYE
Teton, Hebgen, Red Mt, South Arm, Gallatin
13 quakes in the last 25,000 years
1 per 2000 years
1/250 chance per year that one fault in the GYE goes
A low chance doesn’t mean no chance
When will Yellowstone Erupt Again?
It is expected to erupt again
Currently, hot, molten rock is just miles beneath
Potential for a variety of eruptions
Hydrothermal explosions
Lava flows- “Mt. St. Helens volume”
Caldera forming
Least likely
Neodymium deposits in recent flow indicate imminent eruption
Pompeii USA
12 million years ago, eastern Nebraska
Ashfall Fossil Beds State Park
Perfectly preserved flora and fauna
Eruption now
Several feet of ash in Jackson and Bozeman
Global famine caused by the destruction of 50% of the world's cereal grains
Volcanin Odds
No single method to estimate
1 in 146,000 annual chance
70,000 years since the major lava flow
Average 50,000 years
The Future Hotspot
The North American plate is moving 1 inch per year
The new caldera would be in the Beartooths
“Yellowstone Famous Potatoes”
But most basin and range stretched crust has already passed over the hotspot
Now at a cooler and thicker crust
Squeezed not stretched