Obsidian, smooth and shiny black volcanic glass, has fascinated humans for tens of thousands of years. Researchers believe that humans have a natural reaction to shininess that is tied to an innate need–specifically, water. The Eastern Sierra Nevada is a fabulous place to see dark obsidian, especially in areas where it is swirled and folded together with frothy pale gray pumice..
What will define the beginning of the Anthropocene—the proposed subdivision of geologic time marking the onset of significant human impact on our planet’s geology and ecosystems? One possibility is a new material that scientists have named "plastiglomerate".
Machu Picchu is truly one of the wonders of the world. The spectacular ridge-top site of this city and the fine masonry of royal Inca buildings are stunning aesthetic and technical accomplishments. Early Spanish chroniclers reported "molten gold" was used as mortar during stone block construction, and a research paper by a chemist presents some intriguing insights.
Colorful rocks extend across wide swaths of the Southwest, showcased in sedimentary rock formations in Zion, Arches, Capitol Reef, Canyonlands, and other national and state parks. There is an interesting story behind the spectacular bedrock “palette” of rich shades of pink and red, purple and creamy white, and yellow and green tones.
For thousands of years the ancient Andean people revered gold and created exquisite gold art objects. This ultimately led to the fall of the Inca Empire when the metal lured Spanish conquistadores high into the Andes. Gold continues to be mined today, with adverse consequences for the environment and many Andean people.
Iron-oxide concretions – curious-looking dark spheres – can be found by the hundreds of thousands in the dramatic red and white outcrops of Navajo Sandstone in Utah. The concretions typically consist of a sandstone core surrounded by a thick iron-rich rind, and they have an interesting geologic history and Native American cultural history. They also resemble Martian spherules or "blueberries", and may share similar origins.
Towering cliffs, plateaus, arches, and narrow canyons are iconic symbols of southern Utah’s Red Rock Country. Another type of landform captured my attention during recent explorations: mile after mile of gently rolling rock-covered terrain, giving the impression of being surrounded by an ocean of sandstone. An arid sand sea of shifting dunes created these rocks many millions of years ago.
The volcano recently erupting in Africa–Mount Nyiragongo–is one of the most active on our planet. Eruptions in 1977, 2002 and now beginning in May 2021, have resulted in a significant number of fatalities and extensive damage in the nearby and densely populated city of Goma. If scientists were calling the shots, they would relocate Goma and designate the region beneath this active volcano as a national park.
California and other Western US states are facing another major drought, with a snowpack that is approximately 50% of normal throughout the region. The wildfire season is already underway also, stoking fears of fire in treasured places, among them majestic Yosemite Valley.
Rock art by ancient Native American artists includes images of large mammals that are now extinct, the hunting weapons that people used, and much more. We can learn valuable information about ancient lives, traditions, and landscapes from rock art images when they are fit into the context of cultures and time.