Yardang

A yardang is like a big, sandy hill or mountain that's been shaped by the wind. Imagine that you're at the beach and you're trying to build a sandcastle. You might take a handful of sand and let it drop in a pile. Now imagine that the wind is really strong and it's blowing that sand pile around. After a while, the sand will start to erode away in some places more than others, so it will look like a big, tall hump. That's kind of what a yardang looks like! And just like the sand castle, if the wind keeps blowing hard, the yardang might change its shape and size over time.