So then, what is to prevent wind from flowing down the channel......short of a glass tube. Last time I checked, wind is
just air flowing like a fluid.

Did you bother to look at the pictures?

Don't it make you the least bit doubtful?

Stan said;

"From the very nature of dunes, they are located in open, wind blown areas. These pics are in dry eroded channels or deep ravines, protected from wind. I'm quite surprised you don't find these pics interesting and wish to simply pass them on by."

Sure, protected from transverse wind, not wind blowing in the same direction as the channel. As you'll notice, ALL the dunes are "flowing"
in a direction consistent with flow down the channel. But I guess the
Martians could just like to tiger stripe their glass tubes.

Don't just take everything you see and try to place it in a context that
is friendly to your "convictions". Try using some critical thinking skills.
The sooner you do, the sooner you'll see that Cydonia Dick and his ilk are just spewing science fiction, and not even good SciFi at that.

I could recommend some authors.....

BTW, Nick drops 100 slide PowerPoint bombs in defense of statements for a living.