VARIABLES AFFECTING GROWTH OF LITTORAL SPITS

A littoral spit is a narrow peninsula of sand and/or gravel directed parallel to the general shoreline, attached to the main shore at its updrift end, and isolated in the open water at its downdrift end. The two main factors affecting the growth of littoral spits are: (1) abundant source of sand and possibly gravel, and (2) longshore transport dominantly in one direction (equivalent to saying that the site is sheltered from waves in the opposite direction). Sites with recent beach nourishment are good candidates for spit growth. Littoral spits are well developed on tideless lake and tidal ocean shores, so tide range is not likely to be a first order factor determining spits. Spit growth will be favored where nearshore profiles are flatter.

The littoral spit detaches from the main shore at a surprisingly small angle -- typically ten degrees or less at point of tangency. This is similar to the typical angle of nearshore depth-controlled wave breaking. It suggests that littoral spits owe their development to sediment-laden longshore currents whose momentum flux overpowers cross shore factors.