Make up your minds, is it sand or is it gravel? Maybe going to the left (on the street in the foreground) it is sand and going to the right (on the street in the background) it is gravel? Could it be that it all started out as gravel and the through trucks (prohibited from driving on the street in the background) are crushing the gravel into sand when they drive over it on the foreground street? So many signs… so many questions.