There were lineations all over the place. Some of them were outcrops of the underlying rocks, on the whole seeming to dip to the south. Others were obviously faults stretching away into the distance but some of which were offset or acted to offset other faults coming in at an angle. As we were crossing the sand sea or erg I was puzzled by great areas of blobs until a larger one resolved itself into a barchan dune and then I realised what I was seeing – quite obvious when one has one’s eye of faith focused – a dune field. The horns of their crescents were pointing roughly to the south-east and therefore responding to the trade winds.

Presumably where the sand was more plentiful seif dunes had formed, their long axis aligned north-east to south-west parallel to those same winds. Quite a large proportion of the dunes seemed to have ripple marks at an oblique angle to their crests and some dunes seemed to have smaller ones on top – like fleas!
These pick-a-back dunes were in a slightly different orientation. All the dunes themselves were golden but the valleys between were a grey-green colour and (slightly educated guess!) probably of finer grain size being the smaller fraction of the windborne particles.

At one point I could see someone motoring down there (whatever it was, was moving quickly and in a straight line) absolutely miles from anywhere, and elsewhere some camels wandering over the side of a dune (a group of some animate objects moving erratically, slowly and spasmodically). Call me Mrs
Sherlock Holmes. Most bizarre of all was an isolated roughly circular green knoll which appeared to be cultivated – evidence perhaps of an artesian well.
In one of the interdune valleys there was a formation which I immediately labelled ‘sole mark’ but on a grand scale. For those of you who have not had the benefit of sitting at the feet of Brian Williams, sole marks are left by fast, eddying currents, in which vortices erode the substrate leaving identifiable depressions which are then infilled and preserved by sediments deposited later when the velocity of the current subsides. This wasn’t water over sediments but wind over loose ground cover producing the same effect or so I reasoned. That’s one solution – but another has just occurred to me. It could be that the valley was not flat but sloped a little and I was seeing a resistant bed making a typical ‘V’ outcrop over the valley floor or indeed the other way round – a flat valley and a dipping bed of rock. Much more likely, really. But I want it to be a sole mark.

The Gambia is somewhere you go to chill out in 80° F+ temperatures. The people are poor but very friendly. The tourist centres are near the coast which is flat for the most part and has acres of mangrove swamps but it is worth going on a bush safari to see some of the interior. That’s it. Where are we going for our next trip?