pier on rock

[Leo]

  Looks like I have a rock ledge 16 to 36 incheds down what is the procedure here for piers?

[glenn-k]

You could just go with standard design footings or engineered footings, or if you want to make use of the bedrock, you could drill it with a rotohammer  and epoxie rebar into it then pour your concrete piers.  I don't really think the latter is necessary in the case of a small cabin but it is possible if that is your desire.

At any rate it looks like you have a stable foundation.  Are you in a seismic zone?