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Washboarding effect on a road. Washboarding or corrugation [1] is the formation of periodic, transverse ripples in the surface of gravel and dirt roads.Washboarding occurs in dry, granular road material [2] with repeated traffic, traveling at speeds above 8.0 kilometres per hour (5 mph). [3]
Woman on an Israeli kibbutz using a washboard to do laundry. A washboard or a scrubbing-board [1] is a tool designed for hand washing clothing. With mechanized cleaning of clothing becoming more common by the end of the 20th century, the washboard has become better known for its secondary use as a musical instrument.
Part of the road network was built by cultures that precede the Inca Empire, notably the Wari culture. During the Spanish colonial era, parts of the road system were given the status of Camino Real. In 2014 the road system became a UNESCO World Heritage Site. [71] In Peru part of the Inca road system crossed the Andes to connect areas of the ...
He understood the importance of good drainage, knowing it was precipitation that caused most problems on the roads. He worked out a way to build a road across a bog using a series of rafts made from ling (a type of heather) and furze (gorse) tied in bundles as foundations. This established his reputation as a road builder since other engineers ...
Map of early human migrations based on the Out of Africa theory; figures are in thousands of years ago (kya). [1]The peopling of the Americas began when Paleolithic hunter-gatherers (Paleo-Indians) entered North America from the North Asian Mammoth steppe via the Beringia land bridge, which had formed between northeastern Siberia and western Alaska due to the lowering of sea level during the ...
The human story became a bit more complicated about two decades ago. In 2003, archaeologists excavating inside Liang Bua, a cave on the Indonesian island of Flores, found a tiny humanlike skull.
Human history or world history is the record of humankind from prehistory to the present. Modern humans evolved in Africa around 300,000 years ago and initially lived as hunter-gatherers . They migrated out of Africa during the Last Ice Age and had spread across Earth's continental land except Antarctica by the end of the Ice Age 12,000 years ago.
The southern route dispersal is primarily linked to the Initial Upper Paleolithic expansion of modern humans and "ascribed to a population movement with uniform genetic features and material culture" (Ancient East Eurasians), which was the major source for the peopling of the Asia–Pacific region.