Delta in a desert: Okavango

I'm racing against the clock here to get this particular delta posted before Ian uses up the entire world's supply of cool deltas... Hopefully this post makes it up in time!!

The Okavango Delta of Botswana is unusual because the river that feeds it never makes it to the ocean or even a lake. The basin it debouches into is dry as a bone, part of the Kalahari Desert. The classic features of a delta (distributaries, etc.) are still there, but it is a singular feature on the planet Earth to have a delta of this size dry up in the middle of an arid area.

The water provided by the delta encourages plant growth, making for high-contrast satellite photography, as well as making it a refuge for wildlife.

Interestingly, there are ~east-west linear features running across the un-delta'ed landscape, and I'd be pleased if someone could explain what they are. Also, check out the southeastern part of the delta, where several large parallel fractures (trending northeasterly) appear to control the drainage pattern.

Flash Earth location is here:
http://www.flashearth.com/?lat=-19.64623&lon=22.842506&z=8.2&r=0&src=yh

McKenzie Delta

This month's pathological theme is deltas.  Fortuitously, last month, I was looking for high-latitude eolian features without much luck.  Searching for areas I thought would have high winds, high sediment delivery, and low vegetation, I came across the McKenzie River delta.  What a mess!  This is an odd mixture of fluvial and deltaic features, along with periglacial morphologies that looks like it would be heaven for mosquitoes and waterfowl during the summer months.  Not so much for a person with no fondness for mosquitoes or mud.  Still, from orbit, the area is strangely, abstractly, beautiful.

Pathological deltas...the theme for April.

The delta of the Volga River has a particularly interesting juxtaposition of fluvial landforms and beach ridges along its lateral margins. Deltas have a multitude of intriguing and surprising forms...go check some out and, if you are blog member, post some extreme examples.

Where is the Volga River Delta? I forgot.

Takla Makan...River v. Dunes

This area provides a spectacular perspective on a continuing 'battle' between a river and an erg (or 2). In this case, the Tarim River is persistent enough to maintain a coherent channel in the midst of a massive erg. Lots of abandoned paleochannels have been retaken by the aeolian sands. 

OK, back to Xinjiang-Uygur.

Wind-Blown Ash

Have you ever heard of the Huaynaputina eruption of 1600 AD, which may have had global consequences? Well if you're ever driving in the Panamerican Highway between the Arequipa and Moquegua departments in southern Peru, you'll be constantly reminded of it. That happened to me last year when during a trip I noticed these gray dunes, some even barchan-shaped, resting on the flanks of rock formations, mostly on one side of the highway. I knew that wasn't common sand, and later I found out it was ash from the Huaynaputina. Sadly, I didn't take any photos (now I wonder why...) but Google Earth provides a great view. 

I really like the 1st image because you can actually see the ash getting blown by the wind from NNE to SSW, almost painting the landscape. The 2nd image is a zoomed view of the highway, where the ash gets trapped in the rock flanks facing north, developing dunes. The 3rd image is a regional view with the Huaynaputina volcano on the NE corner, and the area I highlighted to the SW.

Check it out on Google Maps.