The pro-cycling peloton is racing the Al'Ula Tour in Saudi Arabia this week, territory of spectacular cliffs of sandstones, deserts, and young volcanoes. The cliffs around AlUla formed in shallow seas, ~500 million years ago, but to the South Polar, as part of the supercontinent 'Gondwana'. - ThreadSky

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geotdf.bsky.social • 33 days ago

The pro-cycling peloton is racing the Al'Ula Tour in Saudi Arabia this week, territory of spectacular cliffs of sandstones, deserts, and young volcanoes.

The cliffs around AlUla formed in shallow seas, ~500 million years ago, but to the South Polar, as part of the supercontinent 'Gondwana'.

Comments

oliviak.bsky.social•33 days ago

Very interesting. Thanks very much. So glad I've found your feed. Looking forward to the season even more now.

geotdf.bsky.social•33 days ago

The Quweira Sandstonesare particularly resistant. These were were used for the famous settlements of Madain Saleh, not far from AlUla. This city was built in the 2nd century CE by the Nabateans, and has beautifully been preserved in the durable, hard rocks.

geotdf.bsky.social•33 days ago

Sandstones of the next-younger Saq Formation is an Arabian lifesaver: these rocks are porous, and serve as the main aquifer (that is, a groundwater-bearing layer) of NW Arabia. These sandstones are rich in trace fossils: tracks in the sand made by ‘trilobites’that roamed the Cambrian sea floor!

larholme.bsky.social•31 days ago

And full of brachiopods! Paper in next issue of Lethaia!

geotdf.bsky.social•33 days ago

NW of Alula, the peloton will see dormant volcanoes of the Harat Uwayrid volcanic field of only 8-0.3 million years old. These are thought to relate to ‘plume’ volcanism, with calm basalt lava flows like on the Canary Islands! Familiar ground for those who trained on the #Teide !

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