In arid sub tropical terrain, moisture collects in pits dug and walled in the volcanic ash. In each hollow, a vine is planted.
For this I threw watercolour at the page, creating the sky, crude green pyramids and a pink and brown ground. When dry, I drew in with charcoal and chalk to define the landscape. A bit of white and black gouache was used to create the stronger contrasts.
I have taken much inspiration from this recently formed and dynamic terrain.
https://kestrelart.wordpress.com/2012/04/18/a-rip-in-the-ground/
https://kestrelart.wordpress.com/2011/10/17/volcanic-landscapes/
https://kestrelart.wordpress.com/2012/04/07/drift/
https://kestrelart.wordpress.com/2011/10/05/inked-with-sepia-and-paynes-grey/
kestrelart 
This is some of your best stuff. At least, I think so. Cultivation on ash is top notch.
Thank you. This is really appreciated.
Great idea. Must look surreal in real life. Great painting
Thanks. The earlier post called “volcanic landscapes” includes a sketch done on site showing a landscape pocked by these dew-catching pits. That sketch is a bit rough (especially the sky) but I like it for the memories of painting it. It is framed above my work station. I have been planning for ages to do a big piece showing that.
The first time I went to Lanzarote I was stunned. It is so different to anything I have seen before.
I appreciate your comments.