Surfaces question

[𝖙𝖋𝖈]

Hey, been experimenting with surfaces and had a couple of questions..

Am I right in thinking the 'sand' surface doesn't yet have dirt buildup or particle effects? The bike really digs in with sand but unfortunately so does the front end!

Is 'gravel' supposed to be actual stone gravel? It seems to handle more like asphalt or concrete and I guess again it doesn't really need buildup, but doesn't have particle effects yet?

What surface material out of soil, compact soil and soft soil is the most giving when it comes to making ruts and riding in them? I thought it would be a good idea to give all my layers the same material (soft soil) but after the first 2 layers were gone it was like riding on ice.

Thanks 

[PiBoSo]

Dry sand and gravel particles should be generated.
There is no dirt buildup from sand and gravel.
Gravel should simulate stone gravel.

[𝖙𝖋𝖈]

Thanks for the answer.

I've used sand and gravel as it states on the wiki page, for example:

material_layer1
{
    material = gravel
   thickness = 0.10
}

and

material_layer2
{
   material = sand
   thickness = 0.6
}

(These are not examples used in one file togehter, used one surface type at a time on all layers)

Unless I'm doing something wrong, neither generate any particles and gravel gives an unbelievably high level of grip.