Reluctantly, Ive accepted the notion that the earth's dynamo is a "random, self reversing dynamo" and as such, does what it does when it does it. In that light, it isn't overdue for a reversal, and there is no "average" length of time in regular or reverse polarity
Hey andro---If you have any questions about my posts in the "Searching Science" sub-forum--please let me know---my posts are a little cryptic.