2-D and 3-D Trend Analysis - Geomathematics: Theoretical Foundations, Applications and Future Developments - page 243

Fig. 7.7 (a) Schematic contour map of Mount Albert Peridotite; elevations are in feet above
sealevel. (b) Variations in specific gravity along section CD (see a for location); all values within
2,500 ft. Source: section line were perpendicularly projected to it. (c) and (d). Cubic trend surfaces
for 300-ft. and 2,000-ft. levels obtained by contouring three-dimensional cubic hypersurface in
two horizontal planes. In most of the area, to-day's topography resembles the 3,000-ft. pattern
more closely than the 2,000-ft. pattern. (e) Crosses represent averages fort values within blocks
measuring 5,000 ft. on a side (see b). Curve 1 is intersection of quintic trend surface (Fig. 7.6 ) with
CD; curve 2 represents variation along topographic surface (see a) according to three-dimensional
cubic hypersurface (Source: Agterberg 1974 , Fig. 46)