A small change in a chart symbol can mean a very large change in what the symbol represents. Rock symbols are a particularly good example of that, as shown in the next section of this tour. In other words, chart symbols are very literal in their meanings and applications. Here we illustrate that by showing how two significant features of what we can see on the water way are reproduced on the chart.
A tiny circle is the symbol of a "dolphin," which is a bundle of piles. In other words, marks and shapes on a chart are almost never decoration, they mean something, and Chart Trainer is where you look to see what they mean.