A lake from long ago in the middle of the dunes

A lake from long ago in the middle of the dunes

Long-sustained westerly winds shaped the dunes surrounding Saudi Arabia’s Jubbah oasis in this photograph taken by an International Space Station (ISS) astronaut. Jubbah sits in the protective shadow of the wind by Jabel Umm Sinman, which roughly translates from Arabic as “mountain with two camel humps.” The hard black rock of the mountain disrupts the flow of the wind and blocks the formation of dunes on its leeward side. The area around Jabel Umm Sinman has been at the center of significant climatic and anthropological changes during the Holocene, a geological term for the last 10,000 years.

Jubbah is built in the basin of a paleolake in the middle of the Nefud desert, about 650 kilometers (400 miles) northwest of Riyadh. A paleolago is an area where a lake previously existed, but no longer contains water due to a change in climate. Today, the ancient lake bed rests hundreds of feet below the neighboring dunes.

Before the desertification of the Arabian Peninsula, Lake Jubbah was part of a network of freshwater sources in what was then a more humid environment. Even as the region became more arid, Lake Jubbah likely continued to retain fresh water for some time due to its position amid the groundwater recharge dunes. This prolonged and continuous period of fresh water made Jubbah a destination for the first humans and animals in the Nefud desert.

Between the dunes to the north of the city, a road runs north-south through the desert, following a path historically traversed by caravan traders. The road and modern agriculture, evident in the revealing center pivot irrigation circular fields, are just the latest iteration of human activity in the area. The mountain also contains petroglyphs that record the lifestyle and culture of the first inhabitants. The petroglyphs, declared a World Heritage Site by UNESCO, have been central to archaeologists and historians seeking to understand occupation and settlement patterns in the region.

Astronaut photograph ISS064-E-6310 was acquired on November 26, 2020 with a Nikon D5 digital camera using a 400-millimeter lens and is provided by the ISS Crew Earth Observations Facility and Unit Earth Sciences and Remote Sensing, Johnson Space Center. The image was taken by a member of the Expedition 64 crew. The image has been cropped and enhanced to improve contrast and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Laboratory to help astronauts take photographs of the Earth that will be of great value to scientists and the public, and to make those images freely available at Internet. Additional images taken by astronauts and cosmonauts can be viewed at NASA / JSC Gateway to Astronaut Photography of Earth. Caption by Alex Stoken, Jacobs, JETS contract at NASA-JSC.

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