Snow Layer Properties

Does anyone know the snow layer properties/nbt tags/etc for all the layers of snow?
I want to have an entity(specifically a cow) to drop a layer of snow and if a layer of snow is already there,another layer will be added. 
I’m guessing that it’s not as simple as just having another layer added, so I’ll have to detect how many layers are in a current block and then add a layer. 
The idea is to retexture the snow layer as manure and wanting the manure to build up overtime if not harvested.