Hello John - My husband is (was) a geologist. He is semi-retired now and only does a bit of consultancy work. So ... I pick his brains and where he doesn't have first hand knowledge he can usually point me in the right direction for further research. I must say being part of TE has helped me to understand the uniqueness of Namibia better than I did and I am becoming a mine of (useless) information! I was lucky with the sky, so often it is blue from corner to corner and more than enough to make a sailor suit! Warm regards Rosemary