The bottom is of rocks, gravel, and mud; the shoaler portions are sharp and rocky.
The tide was now running out, and consequently the more we neared the shore, the shoaler the water got.
The shoaler areas are usually indicated by sanding the outer limit or the entire area within the depth curve.
The bottom is rocky on the shoaler parts, with gravel and pebbles on the edges.
"place of shallow water," c.1300, from Old English schealde (adj.), from sceald "shallow," from Proto-Germanic *skala- (cf. Swedish skäll "thin;" Low German schol, Frisian skol "not deep"), of uncertain origin. The terminal -d was dropped 16c.
"large number" (especially of fish), 1570s, apparently identical with Old English scolu "band, troop, crowd of fish" (see school (n.2)); but perhaps rather a 16c. adoption of cognate Middle Dutch schole.
"assemble in a multitude," c.1600, from shoal (n.2). Related: Shoaled; shoaling.