support for laying track

I would like to lay my track on treated 4x4s two feet off the ground. I realize I will have to put cement to support the 4x4s because of the frost in my area. It goes below zero in the winter and above ninety in the summer. What would you recommend putting on top of the 4x4s to support the track? How wide and thick and what type of wood? I am working with G scale track. Any help would be appreciated. Thank you. Michael

Hi. I talked to someone from a club layout in San Antonio TX. They used 3’ track sections and had to cut them to 1’ becaouse of the expansion/contraction in the TX heat. He said save work and get 1’ track to start with.

Joe Greer SC