Why are some deserts rocky while others are covered in sand dunes?
Quick Answer
Deserts get their surface material from local rock, wind transport, and how much sediment is available. Sandy deserts need a supply of fine grains and winds strong enough to sort and pile them up.
The Full Story
A desert is defined by low rainfall, not by sand. Many deserts are mostly rocky or gravelly because wind has removed the fine material and left a desert pavement behind. Large dune fields form where loose sand is abundant and wind patterns can move it into drifts, such as in parts of the Sahara and Namib deserts. The source of the sand often includes ancient river deposits, weathered bedrock, or coastal sediments.
Key Facts
YouTube Angle
Suggested video title for this topic:
"Not all deserts are sandy — some are the rockiest places on Earth."
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