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.
The risk of megafloods is increasing dramatically as global temperatures rise and store more moisture in the atmosphere. We are not as prepared as many assume. For California, both history and modeling studies of the storm events we can expect in the future provide interesting insights.
Flooding that filled the Central Valley region of California to the point of becoming an inland sea, with water lapping from the Coast Ranges to the Sierra Nevada foothills, was part of Native American oral traditions. And that is exactly what happened in the Great Flood of 1862. If a similar major flood occurs, there will be catastrophic consequences.
California encompasses tremendous diversity, and this includes rocks of virtually every age, reflecting a long and dynamic geologic history. I'm fond of all types of rock, but my favorites are shales, sandstones and limestones that preserve evidence of ancient plant and animal life. The older the fossils, the more interesting.
