2 surfaces intersect query - PL elevation

[rdavisMX6RG]

Hi,

I have 2 surfaces (EG & NG). I want to see the line of intersection between them.

Analyze>Ground Data>min dist between surfaces.

Select both and PL drawn at elevation of intersection. (El of 139.755)

Problem I have is on the EG surface the spot at that point is 139.38 & on the NG the spot there is also 139.38

Is the there a reason why the intersection line would be +.375 higher?

[GKNIGHT892NE]

I would calculate a volume using the two surfaces, the boundary (border might be a better description of the line) of the volume would be the line of intersection between the two surfaces. I think.