This pseudo-dendrite has formed from a combination of water precipitation and very fine dust. During an outback drive, the morning mist has precipitated and dripped on the slightly rounded black plastic surface. The continued movement of the car has shaken another few drips loose and kicked up sufficient fine dust to stick to the water trails. Lighter trails indicate areas which were wet longer and able to trap a thicker dust layer.
Interestingly, the water trails only diverge and never appear to merge. My current hypothesis is that the water trails were pushing tiny iron rich dust particles in front and to the sides of them. When being transported, these would rotate to align with the earths magnetic field but as they dried, this ability would be reduced. A cross section of a dried trail would look a lot like a brontosaurus, thin and pointy at both ends and much thicker in the middle. Not only would this present too sharp an incline compared to the black plastic surface, the dust would have a very minor magnetic field which would contribute to guiding the actively moving droplet away.
Interestingly, the water trails only diverge and never appear to merge. My current hypothesis is that the water trails were pushing tiny iron rich dust particles in front and to the sides of them. When being transported, these would rotate to align with the earths magnetic field but as they dried, this ability would be reduced. A cross section of a dried trail would look a lot like a brontosaurus, thin and pointy at both ends and much thicker in the middle. Not only would this present too sharp an incline compared to the black plastic surface, the dust would have a very minor magnetic field which would contribute to guiding the actively moving droplet away.
