For thousands of years, ancient people collected and transported enormous rocks from quarries to carve their gigantic statues and shape blocks for pyramids, temples, and other monumental structures. The ancient Egyptians are particularly renowned for their work with massive blocks. They used around 200 different quarries over 3,000 years, and worked sandstone, limestone, basalt, granites, and many other types of rocks .
Sand surrounds us–and while it may seem in infinite supply, it is not. Currently, sand is being used up much faster than it is being replenished. Sand and gravel, collectively known as aggregate, are the most widely extracted solid materials on Earth. A recent report by the United Nations Environment Programme recognizes sand as a strategic resource–and one with looming challenges.
The second-most-used substance on Earth is concrete; the first is water. Enormous volumes of cement and concrete are produced each year, and amounts are rising significantly with population growth and emerging economies. Concrete is a major greenhouse gas contributor to climate change, so reductions in this footprint are critically needed.
When I first visited the Peruvian Andes, I was astonished to see groves of eucalyptus — native Australian trees — at elevations greater than 10,000 feet (3,048 m). Eucalyptus is the most widely planted non-native tree in coastal California, which has a Mediterranean-type climate like that found in parts of Australia, but why are these trees in the high Andes?
Geoglyphs are large designs typically longer than about 13 feet (4 m) and produced on the ground by arranging rocks or soil. They are distinctive elements of the archaeological record along the Pacific coast of the Americas, from California to Chile. The Nazca lines of Peru are famous geoglyphs of animals and geometric shapes, constructed in the arid deserts of south-central coastal Peru between about 500 BCE and 500 CE.
Popocatépetl, in southern Mexico, is North America’s 2nd-highest volcano. This volcano has been erupting for millennia—and the recent activity beginning in late May 2023 is bringing additional concern about the possibility of a significant eruption. The tectonic setting of this volcano has some interesting and unusual characteristics.
The enormous dinosaurs that once roamed our planet all died out about 66 million years ago. Fossils of these extraordinary animals are rare. Recently, wealthy collectors have expanded into natural history—and are acquiring unique fossil skeletons for private collections. The remains of ancient creatures are an important part of our history; they are irreplaceable and their value for science is priceless.
Bright blue ponds looming out of the red desert landscape near Moab, Utah, recently prompted my interest in the potash harvested from the pools. The potassium-bearing contents of the ponds will become a key ingredient of synthetic fertilizers. These are essential to feed the growing population on our planet, but fertilizer components are not in infinite supply, plus are causing many environmental problems.
The global need for lithium-ion batteries is projected to grow by over 500% in the next decade, creating a soaring demand for new battery factories and key components of batteries, especially metals. Establishing sustainable battery-supply chains is an important goal. Fortunately, metals are infinitely reusable, and so billions of dollars are being poured into new battery recycling plants.
Around 13,000 years ago, Paleoindian hunters were making red ochre from iron-rich hematite collected from a quarry in the western foothills of the Rocky Mountains. Red ochre had an important role in Paleoindian societies, and is associated with many campsites, kill sites, graves, caches—and notably, found in rock art. Worldwide, the historical record of red ochre mines extends back tens of thousands of years.