**Abstract**

This chapter is aimed at demonstrating how the second vertical derivative method is been applied to gravity data for subsurface delineation. Satellite gravity data of some part of Northern Nigeria that lie between latitude 11°–13°E and longitude 8°–14°N obtained from Bureau Gravimetrique International (BGI) were used for demonstration. The Bouguer graph was plotted using surfer software. The second vertical derivative graph was also plotted. Very low gravity anomalies are observed on the Bouguer map, which recommends the presence of sedimentary rocks which have low density. The result of the second vertical derivative method has improved weaker local anomalies, defined the edges of geologically anomalous density distributions, and identified geologic units. This is a clear implication that the second vertical derivative is very important in subsurface delineation.

**Keywords:** gravity data, second vertical derivative, interpretation
