And JW just for your info you are right the figures he used was 1000 x 1000 x 1000 and if you remenber the anomaly is 1200 x 1700 x 1500 and open to depth as i remember the explanation of the one anomaly. So his numbers were to make things a little simpler, and the calculations were not as big as the anomaly so there may be more than that..