The parasequence is one of the fundamental stratal units in sequence stratigraphy. Although individual parasequences are generally below the resolution of seismic lines, sets of stacked parasequence are distinguishable by their characteristic stratal patterns. Geologists working with well logs base much of their interpretation on the recognition of individual parasequences, their vertical and lateral facies relationships, and their stacking patterns. Thus the parasequence is of prime importance in recognizing sequences and interpreting depositional and tectonic history from sequence development.