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Physical Terrain and Geology

Posts about the physical High Sierra. Rocks, formations, inclusions, and observations about the geology and geography of the Sierra Nevada.

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Longest Orbital Cycles Proven and Measured; Half-Billion Year Super-Milankowitch Cycles sticky icon


What Caused an Ice Age Expansion from 40 to 100 Thousand Years,
“Despite Orbitally Paced Drivers?”

A Gradually Precessing Elliptical Orbit
A gradually precessing elliptical orbit, WillowW, Wiki.
Thanks to WillowW, Wiki

Original Research

Longest Orbital Cycles Proven and Measured

Super-Milankowitch Cycles a Half-Billion Years Long Explained,
& the Shorter Epi-Cycles subdividing the Super Cycles,

In ancient rocks, scientists see a climate cycle working across deep time,
The Earth Institute at Columbia University, May 7, 2018.


"Scientists have for decades posited that Earth's orbit around the sun goes from nearly circular to about 5 percent elliptical, and back again every 405,000 years."

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Land Use, Erosion, and Climate Change's Ancient and Modern Relationship sticky icon



Is this What Happened to Summer, Ur, & Babaylon?
Is this What Happened to Summer, Ur, & Babaylon? Photo by Rick Bohn / United States Fish and Wildlife Service.
Erosion caused by agriculture is a major cause of land degradation. Photo by Rick Bohn / United States Fish and Wildlife Service.


Its Ancient Beginning: Massive Climate Feedback Loop Well Underway

Human Activities Boosted Global Soil Erosion Already 4,000 Years Ago,
Institut national de la recherche scientifique - INRS, October 28, 2019.


Ancient Land Use Erosion
"...recorded temporal changes of soil erosion by analyzing sediment deposits in more than 600 lakes worldwide. They found that the accumulation of lake sediments increased significantly on a global scale around 4,000 years ago. At the same time, tree cover decreased as shown by pollen records, which is a clear indicator of deforestation. The study suggests that human practices and land-use change have intensified soil erosion long before industrialization."

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High Sierra Nevada Backpacker and Hiker Geology Sources, Information, NEWS, and Resources sticky icon


This is the "go to" general page for geological sources, resources, and information.  For now we can use it to store information before it's sorted any further or lost to indexing.

Everyone entering the High Sierra should know something about its Geological History, its Current Geo-Status, and its Future Geological Potentials. In fact, backpackers everywhere should equip themselves with some, "foundational" information about the geology of their region, as well as its contemporary seasonal stellar configuration.

Everything we navigate today was first formed, and is being subsequently sculpted, by these profound Geological Forces, after this batch of star dust consolidated. In other words, our knowledge of the history of the ground and the sky provide an almost timeless context for our natural surroundings, the same Earth & Sky that provides the, "bookends," of our daily hiking experience. The more we know about it, the more deeply we can appreciate its beauty and power.

High Sierra Geology Introductory Texts, Links, & Resources

On the Trail Guide

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Multidirectional Ridgecrest Quake Triggered Garlock Fault Movement



The Danger Zone, 2018
What are your chances of experiencing Moderately-Damaging Ground Shaking in 2018? USGS
What are your chances of experiencing Moderately-Damaging Ground Shaking in 2018? USGS, original.


Multidirectional Ridgecrest Quake Triggered Garlock Fault Movement

Lessons from Ridgecrest,
California Institute of Technology, October 17, 2019.


"...a comprehensive analysis of the Ridgecrest Earthquake Sequence by geophysicists from Caltech and JPL..."

The Ridgecrest Earthquake
"The Ridgecrest Earthquake Sequence included a magnitude-6.4 foreshock on July 4, followed by a magnitude-7.1 mainshock nearly 34 hours later, and more than 100,000 aftershocks. The sequence rattled most of Southern California, but the strongest shaking occurred about 200 kilometers north of Los Angeles."

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May, 2019: Important Recent West Coast Seismic Activity?



Important Recent Seismic Activity?

Small tremors along West Coast could lead to 'big one.'
This is called a "slow slip" event,
KOIN, May 22, 2019.


"A small burst of tremors have been recorded along the West Coast in the last few weeks, causing scientists and geologists to pay close attention."

"This is what we call a slow slip type of movement."

"...scientists predict the "big one" will likely occur during one of these slow slip events."

"He cautioned that the slow slip events are a good reminder to be prepared and have a plan with family and an emergency kit at your home."


Bottom Line

Life Happens
Be Ready
There's not much we can do to change the odds of a major earthquake occuring, but we can hedge our outcomes as backpackers, by keeping a pack set-up sufficient for the current season, with at least a three-day food supply, ready to go. I call it my, "Safety Pack." Everyone should have one...

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The Big Volcano: The Permian Extinction



Siberian Traps Dooming Gorgonopsids
A volcanic eruption spells doom for a predatory gorgonopsid during the Permian Period, by Margaret Weiner/UC Creative Services.
A volcanic eruption spells doom for a predatory gorgonopsid during the Permian Period, by Margaret Weiner/UC Creative Services.


The Big Volcano: The Permian Extinction

New evidence suggests volcanoes caused biggest mass extinction ever,
University of Cincinnati, April 15, 2019.


“...five known mass extinctions over its (Earth’s) 4.5 billion years.”

252 mya
“The extinction 252 million years ago was so dramatic and widespread that scientists call it "the Great Dying."

Ancient Earth
“...killed off much of the terrestrial and marine life before the rise of dinosaurs. Some were prehistoric monsters in their own right, such as the ferocious gorgonopsids that looked like a cross between a sabre-toothed tiger and a Komodo dragon.”

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Long 100 Year Gap of Major California Earthquakes



The Last Big One
San Francisco Earthquake of 1906
San Francisco Mission District burning in the aftermath of the San Francisco Earthquake of 1906. By Chadwick, H. D, US Gov War Department. Wiki.

San Francisco Mission District burning in the aftermath of the San Francisco Earthquake of 1906. By Chadwick, H. D, US Gov War Department. Wiki, Big Shot.

The last major quake in California was just over a hundred years ago, with the SF Quake measuring in at 7.9. Loma Prieta was 6.9, in 1989.


Long Gap of Major California Earthquakes

California's current earthquake hiatus is an unlikely pause,
Seismological Society of America, April 3, 2019.


A Quiet 100 Years
“There have been no major ground rupturing earthquakes along California's three highest slip rate faults in the past 100 years.”

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Complex Geology of Tahoe Basin, Emerald Bay



Lake Tahoe, Emerald Bay, and the Sierra Crestline
Emerald Bay, Lake Tahoe, USA, Credit to GSA & R.A. Schweickert et al.

Emerald Bay, Lake Tahoe, USA, Credit to GSA & R.A. Schweickert et al, large. Map.


Complex Geology of Tahoe Basin, Emerald Bay

Underwater surveys in Emerald Bay reveal the nature and activity of Lake Tahoe faults,
Geological Society of America, March 16, 2019.


Tahoe Basin
“...Lake Tahoe region is rife with active faults, many of which have created the dramatic and rugged landscapes. The Lake Tahoe region lies between the Sierra Nevada microplate to the west and the Basin and Range Province to the east. Northwestward movement of the Sierra Nevada microplate creates stresses that may produce both strike slip (horizontal) and vertical movement on faults.”

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Growing Land Use Apocalypse Approaches


Land Use Apocalypse

Urban Nighmare - Nature's Reality
LA in 2050?
Land Use Urban Nighmare is Nature's Reality, by Stark8, Pixabay.
Our, "leaders," are trying to create this here; Land Use, Xiamen, China, by Stark8, Pixabay


Due to humans, extinction risk for 1,700 animal species to increase by 2070,
Yale University, March 4, 2019.


Extinction Targets 1700 Species
Cause: Land Use

“The study shows that under a middle-of-the-road scenario of moderate changes in human land-use about 1,700 species will likely experience marked increases in their extinction risk over the next 50 years: They will lose roughly 30-50% of their present habitat ranges by 2070.
These species of concern include 886 species of amphibians, 436 species of birds, and 376 species of mammals -- all of which are predicted to have a high increase in their risk of extinction.”

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2018: Huge Alaska Quake & Swarming Aftershocks


Huge Alaska Quake & Swarming Aftershocks
USGS topo map of Alaska earthquake of December 2018.
USGS Topo Map

First images of slope failures triggered by the M=7.0 Alaska earthquake,
AGU, December 1, 2018.


"The M=7.0 Alaska earthquake on 30th November 2018"

“ was comparatively deep (41 km).”

“...much of the area affected had limited potential for large-scale landslides due to the low relief topography:”


Wild series of aftershocks:



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Is the Long Valley Caldera Hot-Cold Water Boundary Secure?


Is the Long Valley Caldera's Hot-Cold Water Boundary Secure?

Is former Olympian a bully or savior in geothermal fight?
E&ENews, October 29, 2018.


Not Contained?
“Hayes, a charismatic former Olympian, says data show the deep geothermal reservoirs used for energy production are not completely contained. They are already contaminating the town's shallower groundwater aquifers, he says, and the problem could get worse when the plant expands production.”

“...that's what Pat Hayes, the area's water manager, wants you to think.”

“The problem for Hayes, though, is it's unclear how much validity there is to those claims.”

“His critics note that Hayes has secured few victories. Courts have strongly rejected his claims, siding with regulators who reviewed the relevant scientific data, as well as a robust groundwater monitoring plan they've put in place.”

“Judge Stan Eller concluded that "available evidence" indicates the groundwater and geothermal systems are separate.”

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2018 USGS National Volcanic Threat Assessment UPDATE


Mountain Safety & Understanding Our Terrain

2018 Update to the U.S. Geological Survey National Volcanic Threat Assessment,
USGS, October 22, 2018, PDF.

       USGS Abstract-Introduction Page

Information & Awareness
Western US Maps & the Threat List

The main point of this whole exercise is to make citizens and public safety officers aware of the nature and extent of potential local and regional volcanic threats.

This assessment information, along with some good news reporting, may have discouraged some of the folks backpacking Mount Saint Helens the day it blew...

Volcano Hazards Program

Earthquake Hazards Program

Today's Earthquake Map

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How the Great Plains Were Created


How the Great Plains Were Created

The origins of the High Plains landscape,
ETH Zurich, September 26, 2018.


“Dropping just a few hundred meters over a length of more than 500 kilometres, these plains have only a very gentle gradient and the nearly flat surfaces exhibit unique ecosystems, making them a geological and ecological anomaly.”

“...the groundwater reservoir known as the Ogallala aquifer. At 450,000 square kilometres, it is the largest aquifer in North America.”

“The High Plains were formed 20 million years ago. Earth scientists have recently discovered a zone of unusually hot material in the Earth's mantle that creates a wave of uplift that is slowly shifting from west to east under the continental plate. This wave first uplifted the Colorado Plateau, then the Rockies and finally the plains themselves. This resulted in a steeper gradient of the mountains towards the plains, accelerating erosion. For 15 million years, a massive flow of sediment poured out of the mountains, down the river valleys and into the plains.”

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Caltrans Reports


Original Story

June Lake Loop Closed

Portion of State Route 158 closed due to mudslide,
Sierra Wave, July 31, 2018.

 “...closed between Silver Lake and Grant Lake. The official location is 7.3 miles south of the north junction of SR 158 & US Hwy 395.  A large mud slide is covering a large portion of the highway. Caltrans crews and CHP are on site directing traffic.  The highway will remain closed overnight and the situation will be reassessed in the morning.”



Highway 158

All Mountain Highways


Trail Guide

USGS TOPO Hiking Map

Donohue to Island Passes, including trails to June Lake

Trail Guide & Schematic Map

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Big Quakes can Trigger Big Quakes on opposite side of Earth


Bi-Polar Quakes

Research finds quakes can systematically trigger other ones on opposite side of Earth,
Oregon State University, August 2, 2018.

"New research shows that a big earthquake can not only cause other quakes, but large ones, and on the opposite side of the Earth."

"...looked at 44 years of seismic data and found clear evidence that temblors of magnitude 6.5 or larger trigger other quakes of magnitude 5.0 or larger."

"It had been thought that aftershocks – smaller magnitude quakes that occur in the same region as the initial quake as the surrounding crust adjusts after the fault perturbation – and smaller earthquakes at great distances – were the main global effects of very large earthquakes."

"...analysis of seismic data from 1973 through 2016 – an analysis that excluded data from aftershock zones – using larger time windows than in previous studies, provided discernible evidence that in the three days following one large quake, other earthquakes were more likely to occur."

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Pieces of mantle found rising under north and south ends of Cascadia fault


How the Earth Conducts Quake-Stresses

Mantle Composition Affects Fault Behavior

Pieces of mantle found rising under north and south ends of Cascadia fault,
University of Oregon, July 24, 2018.


"...researchers have found anomalies in the upper mantle below both ends of the Cascadia Subduction Zone. They may influence the location, frequency and strength of earthquake events along the U.S. Pacific Northwest."

Scope of Cascadia

"The 620-mile subduction zone, which hasn't experienced a massive lengthwise earthquake since 1700, is where the Juan de Fuca ocean plate dips under the North American continental plate. The fault zone stretches just offshore from northern Vancouver Island to Cape Mendocino in northern California."

More Locking

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Genesis of The Yellowstone Super-volcano: It's a Sinking Plate, Not a Plume


Genesis of a Super volcano

It's a Sinking Plate, Not a Plume

Yellowstone super-volcano has a different history than previously thought,
Virginia Tech, July 25, 2018.

"Scientists have long thought that Yellowstone Caldera, part of the Rocky Mountains and located mostly in Wyoming, is powered by heat from the Earth’s core, similar to most volcanoes such as the recently active Kilauea volcano in Hawaii."

"...Yellowstone volcanoes were produced by a gigantic ancient oceanic plate that dove under the Western United States about 30 million years ago. This ancient oceanic plate broke into pieces, resulting in perturbations of unusual rocks in the mantle which led to volcanic eruptions in the past 16 million years.”

"The sinking section of oceanic plate slowly pushed hot materials upward to form the volcanoes that now make up Yellowstone."


USGS Yellowstone Observatory


Yellowstone Caldera


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2018 Valley Subsidence a Symbol of Overproduction Abuses


Ripping Off the Taxpayer to Continue Draining California


Original Story

Still Got that Sinking Feeling?

Good, As We’ve Destroyed the Natural Foundations of Our Own Bounty & Beauty

The Valley floor is sinking, and it’s crippling California’s ability to deliver water,
Sacbee, July 13, 2018.

Valley Subsidence a Symbol of Long-Term Overproduction Abuses


The Last Chapters

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Forest Expansion: Forni Meadows now part of Eldorado Forest



The El Dorado Forest Expands

The Edge of The Desolation Wilderness

Under the Southern Shadow of Pyramid Peak

Forni Meadows now part of Eldorado Forest,
Lake Tahoe News, July 10, 2018.

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