Tag Archives: geology

09-14-19 – Craters of the Moon National Monument


Craters of the Moon National Monument and Preserve is a U.S. National Monument and national preserve in the Snake River Plain in central Idaho. It is along US 20 (concurrent with US 93 and US 26), between the small towns of Arco and Carey, at an average elevation of 5,900 feet (1,800 m) above sea level. The protected area’s features are volcanic and represent one of the best-preserved flood basalt areas in the continental United States.

The Monument was established on May 2, 1924. In November 2000, a presidential proclamation by President Clinton greatly expanded the Monument area. The National Park Service portions of the expanded Monument were designated as Craters of the Moon National Preserve in August 2002. It lies in parts of Blaine, Butte, Lincoln, Minidoka, and Power counties. The area is managed cooperatively by the National Park Service and the Bureau of Land Management (BLM).

The Monument and Preserve encompass three major lava fields and about 400 square miles (1,000 km2) of sagebrush steppe grasslands to cover a total area of 1,117 square miles (2,893 km2). The Monument alone covers 53,571 acres (21,679 ha). All three lava fields lie along the Great Rift of Idaho, with some of the best examples of open rift cracks in the world, including the deepest known on Earth at 800 feet (240 m). There are excellent examples of almost every variety of basaltic lava, as well as tree molds (cavities left by lava-incinerated trees), lava tubes (a type of cave), and many other volcanic features


09-13-19 – City Of Rocks National Preserve



The City of Rocks National Reserve, also known as the Silent City of Rocks, is a United States National Reserve and state park lying 2 miles (3.2 km) north of the south central Idaho border with Utah. It is widely known for its excellent rock climbing and rock formations.

The rock spires in the City of Rocks and adjacent Castle Rocks State Park are largely composed of granitic rock of the Oligocene Almo pluton and Archean Green Creek Complex.

California Trail wagon trains of the 1840s and 1850s left the Raft River valley and traveled through the area and over Granite Pass into Nevada. Names or initials of emigrants written in axle grease are still visible on Register Rock. Ruts from wagon wheels also can be seen in some of the rocks.

The landscape of City of Rocks has been sculpted from granite that was intruded into the crust during two widely spaced times. The granite that composes most of the spires is part of the 28-million-year-old Almo pluton. However, some of the spires are made of granite that is part of the 2.5 billion-year-old Green Creek Complex that contains some of the oldest rocks in the western United States. The granite has eroded into a fascinating assortment of shapes.

City of Rocks was designated a National Reserve, a unit of the National Park Service, in recognition of the nationally significant geological and scenic values of its rock formations and the historical significance of the California Trail. Rock formations in the reserve developed through an erosion process called exfoliation, during which thin rock plates and scales sloughed off along joints in the rocks. The joints, or fractures, resulted from the contraction of the granite as it cooled, from an upward expansion of the granite as overlying materials were eroded away, and from regional tectonic stresses. The granite has eroded into a fascinating assortment of shapes as high as 600 feet (180 m). The upper surfaces of many of the rocks are covered with flat-floored weathering pits known as panholes. The most notable panhole is located on top of Bath Rock and is continuously filled with water from rain or snowmelt.

Source: Wikipedia

09-13-19 – Basin and Range National Monument


Basin and Range National Monument is a national monument of the United States spanning approximately 704,000 acres (1,100 sq mi; 2,800 km2) of remote, undeveloped mountains and valleys in Lincoln and Nye counties in southeastern Nevada. It is described as “one of the emptiest spaces in a state famous for its emptiness.”

The Basin and Range National Monument area has geological, ecological, cultural, historical, paleoecological, seismological, archaeological, and paleoclimatological significance. The area is located in a transitional region between the Mojave Desert and the Sagebrush Steppe of the Great Basin.

Major features within the national monument include: Garden Valley and Coal Valley; the Worthington Mountains, containing the Worthington Mountains Wilderness Area; the Golden Gate Range; the Seaman Range; the Mount Irish Range; the Hiko Narrows; the White River Narrows; and the Shooting Gallery rock art site. Native American rock art at the site is about 4,000 years old.

Fauna of significance in the national monument include desert bighorn sheep, golden eagle, and many species of bat, lizard, and snake.

Source: Wikipedia

08-18-19 – Mono-Inyo Craters


The Mono–Inyo Craters are a volcanic chain of craters, domes and lava flows in Mono County, Eastern California. The chain stretches 25 miles (40 km) from the northwest shore of Mono Lake to the south of Mammoth Mountain. The Mono Lake Volcanic Field forms the northernmost part of the chain and consists of two volcanic islands in the lake and one cinder cone volcano on its northwest shore. Most of the Mono Craters, which make up the bulk of the northern part of the Mono–Inyo chain, are phreatic (steam explosion) volcanoes that have since been either plugged or over-topped by rhyolite domes and lava flows. The Inyo Craters form much of the southern part of the chain and consist of phreatic explosion pits, and rhyolitic lava flows and domes. The southernmost part of the chain consists of fumaroles and explosion pits on Mammoth Mountain and a set of cinder cones south of the mountain; the latter are called the Red Cones.

Eruptions along the narrow fissure system under the chain began in the west moat of Long Valley Caldera 400,000 to 60,000 years ago. Mammoth Mountain was formed during this period. Multiple eruptions from 40,000 to 600 years ago created the Mono Craters and eruptions 5,000 to 500 years ago formed the Inyo Craters. Lava flows 5,000 years ago built the Red Cones, and explosion pits on Mammoth Mountain were excavated in the last 1,000 years. Uplift of Paoha Island in Mono Lake about 250 years ago is the most recent activity. These eruptions most likely originated from small magma bodies rather than from a single, large magma chamber like the one that produced the massive Long Valley Caldera eruption 760,000 years ago. During the past 3,000 years, eruptions have occurred every 250 to 700 years. In 1980, a series of earthquakes and uplift within and south of Long Valley Caldera indicated renewed activity in the area.

The region has been used by humans for centuries. Obsidian was collected by Mono Paiutes for making sharp tools and arrow points. Glassy rock continues to be removed in modern times for use as commercial scour and yard decoration. Mono Mills processed timber felled on or near the volcanoes for the nearby boomtown Bodie in the late 19th to early 20th centuries. Water diversions into the Los Angeles Aqueduct system from their natural outlets in Mono Lake started in 1941 after a water tunnel was cut under the Mono Craters. Mono Lake Volcanic Field and a large part of the Mono Craters gained some protection under Mono Basin National Forest Scenic Area in 1984. Resource use along all of the chain is managed by the United States Forest Service as part of Inyo National Forest. Various activities are possible along the chain, including hiking, bird watching, canoeing, skiing, and mountain biking.

Source: Wikipedia

08-17-19 – Crowley Lake


Crowley Lake is a reservoir on the upper Owens River in southern Mono County, California, in the United States. Crowley Lake is 15 miles south of Mammoth Lakes.

The lake was created in 1941 by the building of the Long Valley Dam by the Los Angeles Department of Water and Power (DWP), as storage for the Los Angeles Aqueduct and for flood control. The dam is 126 feet high and impounds 183,465 acre-feet. For more on the history of the lake, see Owens Lake.

The lake is named after Father John J. Crowley, “the desert Padre”, who was a key figure in Owens Valley history and a local hero. When it became obvious that the city of Los Angeles’s appropriation of the water supply had made agriculture impossible in the Owens Valley, many of the residents of the Valley lost all hope. Father Crowley traveled up and down the Valley, convincing many of them that it could become a tourist destination. Thus, it is fitting that while it exists to serve the Los Angeles aqueduct, Crowley Lake is also a prime destination for anglers. Father Crowley was killed in 1940 in an automobile accident.

Upon completion of the reservoir in 1941, strange columnar formations, some of which reached heights of as much as 20 feet, were spotted along the reservoir’s eastern shore. Some described them as stone cylinders connected by fortified stone arches that had been completely covered and obscured for millions of years but which had been gradually unmasked by the incessant pummeling of the lake’s powerful waves, whose constant pounding had eroded the more malleable rock at the base of the cliffs encasing these pillars. The pillars were simply regarded as oddities until 2015, when geologists realized that they were the result of frigid water from melting snow seeping down into volcanic ash (the result of a catastrophic explosion more than 700,000 years prior), creating tiny holes in the hot ash, the byproduct being boiling water and steam, which then rose up and out of these same holes. Samples of the resulting “evenly spaced convection cells similar to heat pipes” (a quote from a study at UC Berkeley) were analyzed using X-rays and electronic microscopes; and researchers found that minute crevices in these “convection pipes” were literally bonded into place by minerals that were able to resist the corrosive force of the lake’s waves. Researchers have now counted nearly 5,000 of these pillars, which appear in groups and vary widely in shape, size and color over an area of 4000 acres, with some of the columns standing as erect as towering pylons and sporting ringed apertures approximately a foot apart; others which are warped or leaning at various angles; and still others that are half-submerged and, some say, resemble the petrified remains of dinosaur vertebrae.

Source: Wikipedia

06-15-19 – Alabama Hills National Scenic Area



The Alabama Hills are a range of hills and rock formations near the eastern slope of the Sierra Nevada in the Owens Valley, west of Lone Pine in Inyo County, California, United States. Though geographically separate from the Sierra Nevada, they are part of the same geological formation.

The Alabama Hills are managed by the U.S. Bureau of Land Management (BLM) as the Alabama Hills Recreation Area. The area is managed as a protected habitat for public enjoyment. In March 2019, the US congress, as part of the California Deserts Wilderness Act, redesignated the area as the Alabama Hills National Scenic Area

05-24-14 – Lassen Volcanic National Park




A visit to Lassen Volcanic National Park for a scenic drive-through, stopping at every vista point.

05-04-14 – Petrified Forest National Park




I spent the better part of a day driving through Petrified Forest National Park. It so much more than some tree fossils! Blue Mesa, Painted Desert, pueblos, petroglyphs… it is a gem of our National Park system.