Heidi.
We live in south east Oklahoma and are planning to use Cedar for our logs and a clay plaster mix for chinking. The "rubble trench" and short stone wall that is used in Cob building will be used for the foundation and it will have a cob floor. The "rubble trench" is for drainage and the rock wall is to help keep the logs off the ground and the termites at bay. We have several ideas for a roof but have not decided on any one yet. Good luck with your cabin!